Dr Derrick’s Science Lectures - Invidious

Dr Derrick’s Science Lectures

*Welcome to Dr. Derrick's Science Lectures!*

Join me on a journey to explore the fascinating world of science! This channel is dedicated to helping O-level students, first-year university students, and science enthusiasts understand biology, chemistry, and physics concepts in a clear and engaging way.

*What to Expect:*

- In-depth explanations of complex science concepts covering JAMB, WAEC, NECO, GCE and Cambridge IGCSE Examinations.
- Engaging video lessons and tutorials
- Exam tips and strategies to help you succeed
- Fun and interactive experiments to illustrate key concepts

*Subscribe now* and get ready to unlock the secrets of the natural world!

*Topics Covered:*

- Biology: cell biology, genetics, ecology, and more
- Chemistry: atomic structure, chemical reactions, organic chemistry, and more
- Physics: mechanics, energy, waves, and more

*Join the conversation:* Share your questions, comments, and ideas in the comments section below. Let's learn science together!

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Unable to parse item

Invidious encountered an error while trying to parse this item. For more information see below:

Show technical details

Title: `Missing hash key: "collectionThumbnailViewModel" (KeyError)`
Date: `2026-06-09T11:38:33Z`
Route: `/channel/UC59gCEdSn2tnsdmpJ7Qh09A`
Version: `2026.02.07-118d635 @ (HEAD detached at v2.20260207.0)`

<details>
<summary>Backtrace</summary>
<p>
   
```
Missing hash key: "collectionThumbnailViewModel" (KeyError)
  from /usr/share/crystal/src/hash.cr:1198:9 in '??'
  from /usr/share/crystal/src/json/any.cr:149:5 in 'process'
  from src/invidious/yt_backend/extractors.cr:524:17 in 'process'
  from src/invidious/yt_backend/extractors.cr:1035:17 in 'parse_item'
  from src/invidious/yt_backend/extractors.cr:1082:14 in 'extract_items'
  from src/invidious/channels/videos.cr:29:22 in 'get_60_videos:continuation:sort_by'
  from src/invidious/routes/channels.cr:56:36 in 'videos'
  from lib/kemal/src/kemal/route.cr:13:9 in '->'
  from src/invidious/helpers/handlers.cr:31:37 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call_next'
  from lib/kemal/src/kemal/filter_handler.cr:22:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call_next'
  from src/invidious/helpers/handlers.cr:80:12 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call_next'
  from src/ext/kemal_static_file_handler.cr:127:14 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/request_processor.cr:51:11 in 'handle_client'
  from /usr/share/crystal/src/fiber.cr:170:11 in 'run'
  from ???
```
</p>
</details>

Unable to parse item

Invidious encountered an error while trying to parse this item. For more information see below:

Show technical details

Title: `Missing hash key: "collectionThumbnailViewModel" (KeyError)`
Date: `2026-06-09T11:38:33Z`
Route: `/channel/UC59gCEdSn2tnsdmpJ7Qh09A`
Version: `2026.02.07-118d635 @ (HEAD detached at v2.20260207.0)`

<details>
<summary>Backtrace</summary>
<p>
   
```
Missing hash key: "collectionThumbnailViewModel" (KeyError)
  from /usr/share/crystal/src/hash.cr:1198:9 in '??'
  from /usr/share/crystal/src/json/any.cr:149:5 in 'process'
  from src/invidious/yt_backend/extractors.cr:524:17 in 'process'
  from src/invidious/yt_backend/extractors.cr:1035:17 in 'parse_item'
  from src/invidious/yt_backend/extractors.cr:1082:14 in 'extract_items'
  from src/invidious/channels/videos.cr:29:22 in 'get_60_videos:continuation:sort_by'
  from src/invidious/routes/channels.cr:56:36 in 'videos'
  from lib/kemal/src/kemal/route.cr:13:9 in '->'
  from src/invidious/helpers/handlers.cr:31:37 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call_next'
  from lib/kemal/src/kemal/filter_handler.cr:22:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call_next'
  from src/invidious/helpers/handlers.cr:80:12 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call_next'
  from src/ext/kemal_static_file_handler.cr:127:14 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/request_processor.cr:51:11 in 'handle_client'
  from /usr/share/crystal/src/fiber.cr:170:11 in 'run'
  from ???
```
</p>
</details>

Unable to parse item

Invidious encountered an error while trying to parse this item. For more information see below:

Show technical details

Title: `Missing hash key: "collectionThumbnailViewModel" (KeyError)`
Date: `2026-06-09T11:38:33Z`
Route: `/channel/UC59gCEdSn2tnsdmpJ7Qh09A`
Version: `2026.02.07-118d635 @ (HEAD detached at v2.20260207.0)`

<details>
<summary>Backtrace</summary>
<p>
   
```
Missing hash key: "collectionThumbnailViewModel" (KeyError)
  from /usr/share/crystal/src/hash.cr:1198:9 in '??'
  from /usr/share/crystal/src/json/any.cr:149:5 in 'process'
  from src/invidious/yt_backend/extractors.cr:524:17 in 'process'
  from src/invidious/yt_backend/extractors.cr:1035:17 in 'parse_item'
  from src/invidious/yt_backend/extractors.cr:1082:14 in 'extract_items'
  from src/invidious/channels/videos.cr:29:22 in 'get_60_videos:continuation:sort_by'
  from src/invidious/routes/channels.cr:56:36 in 'videos'
  from lib/kemal/src/kemal/route.cr:13:9 in '->'
  from src/invidious/helpers/handlers.cr:31:37 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call_next'
  from lib/kemal/src/kemal/filter_handler.cr:22:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call_next'
  from src/invidious/helpers/handlers.cr:80:12 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call_next'
  from src/ext/kemal_static_file_handler.cr:127:14 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/request_processor.cr:51:11 in 'handle_client'
  from /usr/share/crystal/src/fiber.cr:170:11 in 'run'
  from ???
```
</p>
</details>

Unable to parse item

Invidious encountered an error while trying to parse this item. For more information see below:

Show technical details

Title: `Missing hash key: "collectionThumbnailViewModel" (KeyError)`
Date: `2026-06-09T11:38:33Z`
Route: `/channel/UC59gCEdSn2tnsdmpJ7Qh09A`
Version: `2026.02.07-118d635 @ (HEAD detached at v2.20260207.0)`

<details>
<summary>Backtrace</summary>
<p>
   
```
Missing hash key: "collectionThumbnailViewModel" (KeyError)
  from /usr/share/crystal/src/hash.cr:1198:9 in '??'
  from /usr/share/crystal/src/json/any.cr:149:5 in 'process'
  from src/invidious/yt_backend/extractors.cr:524:17 in 'process'
  from src/invidious/yt_backend/extractors.cr:1035:17 in 'parse_item'
  from src/invidious/yt_backend/extractors.cr:1082:14 in 'extract_items'
  from src/invidious/channels/videos.cr:29:22 in 'get_60_videos:continuation:sort_by'
  from src/invidious/routes/channels.cr:56:36 in 'videos'
  from lib/kemal/src/kemal/route.cr:13:9 in '->'
  from src/invidious/helpers/handlers.cr:31:37 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call_next'
  from lib/kemal/src/kemal/filter_handler.cr:22:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call_next'
  from src/invidious/helpers/handlers.cr:80:12 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call_next'
  from src/ext/kemal_static_file_handler.cr:127:14 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/request_processor.cr:51:11 in 'handle_client'
  from /usr/share/crystal/src/fiber.cr:170:11 in 'run'
  from ???
```
</p>
</details>

Unable to parse item

Invidious encountered an error while trying to parse this item. For more information see below:

Show technical details

Title: `Missing hash key: "collectionThumbnailViewModel" (KeyError)`
Date: `2026-06-09T11:38:33Z`
Route: `/channel/UC59gCEdSn2tnsdmpJ7Qh09A`
Version: `2026.02.07-118d635 @ (HEAD detached at v2.20260207.0)`

<details>
<summary>Backtrace</summary>
<p>
   
```
Missing hash key: "collectionThumbnailViewModel" (KeyError)
  from /usr/share/crystal/src/hash.cr:1198:9 in '??'
  from /usr/share/crystal/src/json/any.cr:149:5 in 'process'
  from src/invidious/yt_backend/extractors.cr:524:17 in 'process'
  from src/invidious/yt_backend/extractors.cr:1035:17 in 'parse_item'
  from src/invidious/yt_backend/extractors.cr:1082:14 in 'extract_items'
  from src/invidious/channels/videos.cr:29:22 in 'get_60_videos:continuation:sort_by'
  from src/invidious/routes/channels.cr:56:36 in 'videos'
  from lib/kemal/src/kemal/route.cr:13:9 in '->'
  from src/invidious/helpers/handlers.cr:31:37 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call_next'
  from lib/kemal/src/kemal/filter_handler.cr:22:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call_next'
  from src/invidious/helpers/handlers.cr:80:12 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call_next'
  from src/ext/kemal_static_file_handler.cr:127:14 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/handler.cr:30:7 in 'call'
  from /usr/share/crystal/src/http/server/request_processor.cr:51:11 in 'handle_client'
  from /usr/share/crystal/src/fiber.cr:170:11 in 'run'
  from ???
```
</p>
</details>