KastorFlowUpdated November 6, 2026
KastorFlow vs YouTube to NotebookLM
Two extensions for NotebookLM, now Gemini Notebook. We make KastorFlow; YouTube to NotebookLM's features are from its own store listing.
Both send YouTube videos, playlists, channels and search results to Gemini Notebook, which on its own takes one video per link. KastorFlow also merges a playlist into one source, so a 40-video course uses one of a notebook's slots instead of 40, checks the notebook has room first, and captures a video's slides with its transcript. Then it does the rest of the notebook work: audits, filling gaps, research builds, automations and flashcards to Anki.
Feature by feature
| Feature | KastorFlow | YouTube to NotebookLM |
|---|---|---|
| A source per video from a playlist, channel or search results | Yes | Yes |
| Merge a playlist or channel into one source (one for every 100 videos) | Yes | — |
| Capture a video's frames and transcript as one PDF source | Yes | — |
| Check the notebook has room before importing | Yes | — |
| Import a playlist or channel on a schedule, with an automation | Yes | Mentions syncing a channel; no schedule described |
| Save ChatGPT, Claude, Gemini, Perplexity and Grok chats | Yes | — |
| Import a CSV of links, several open tabs or a feed | Yes | The current tab, one at a time |
| Audit a notebook's sources and fill the gaps you approve | Yes | — |
| Build a research notebook from a topic | Yes | — |
| Folders, tags and search across every notebook | Yes | — |
| Find duplicates in a notebook; delete sources in bulk | Yes | — |
| Flashcards into Anki; Obsidian and Readwise | Yes | — |
| Audio Overviews in your own podcast feed | Yes | — |
YouTube to NotebookLM's features as listed on its Chrome Web Store listing (version 1.0.48), read November 6, 2026. — means they don't mention it, not that it can't be done. The KastorFlow column is checked against the extension itself. Spotted something out of date? Tell us and we'll fix it.
What Gemini Notebook does with YouTube on its own
Gemini Notebook takes YouTube one video at a time. We tested 18 links on October 30, 2026 and one more video on November 6.
- Single videos work, including a course of almost 25 hours, Shorts, youtu.be links and links with a start time. Only the transcript comes in: the small print under the link box says so.
- A playlist link misleads. It brought in about 700 words of page text, titles and lengths, and no transcripts.
- A channel link fails: "Unable to import this web page due to domain restrictions."
- No captions, no import: a video with no speech or no captions fails with "Transcript not available."
You can paste several video links at once, separated by a space or a new line. That's fine for five videos; for a 40-video course, copying every link is the job an extension takes off you. YouTube to Gemini Notebook
What the differences mean in practice
Getting many videos in
Both send a video, a playlist, a channel's videos or YouTube search results to a notebook you pick. KastorFlow drops duplicate videos from a run and checks the notebook has room before it starts, so you know whether a long playlist fits. Free includes 3 YouTube runs a month; Pro has no monthly limit.
Separate sources or one merged source
| How to import | Notebook slots used | Good for |
|---|---|---|
| Each video as its own source | One per video | Ticking single videos for the chat; a few videos |
| The whole playlist merged into one source | One for every 100 videos | Long courses and talks in a free notebook |
A free notebook holds 50 sources, and a 40-video course added video by video fills 40 of them. KastorFlow can merge a playlist or a channel's recent uploads into one source, one for every 100 videos, which leaves 49 slots for papers and notes. The trade-off: you can't tick single videos inside a merged source. Free includes 1 merge a month, with a free sign-in; Pro includes 50. A playlist as one source
Slides and on-screen text
A transcript holds what's said, not what's shown. KastorFlow's Capture video frames takes frames from the video and puts them in one PDF source with the full transcript. For a slide lecture, Keyframes only keeps a frame only when at least 10% of the picture has changed, so you get each slide once. Free includes 3 captures a month. Can NotebookLM watch videos?
New videos from a channel
YouTube to NotebookLM's listing mentions syncing a channel without describing a schedule. In KastorFlow, an automation can import a playlist or channel on a schedule you set, every day or every week at a time you choose, so new uploads reach the notebook without you. Automations are on Pro.
After the videos are in
KastorFlow also works on the notebook: an audit that flags weak sources and shows missing kinds, Enrich to fill the gaps you approve, flashcards straight into Anki (Gemini Notebook made 52 from one video in our test but can't export them), and a podcast feed for Audio Overviews.
Try KastorFlow next to YouTube to NotebookLM
You don't have to switch to compare them. KastorFlow works on the same Gemini Notebook tabs and Google account, and reads the notebooks already there. Nothing needs moving.
- Add KastorFlow to Chrome. No account is needed to start.
- Try a playlist as one source. Open a YouTube playlist, click the KastorFlow icon in Chrome's toolbar, choose Import playlist as one source and pick the notebook. It checks the notebook has room before it starts.
- Capture a lecture's slides. Open a slide-heavy video, open KastorFlow's side panel and choose Capture video frames. Turn on Keyframes only and keep the video's tab in front while it runs.
- KastorFlow keeps its own tags, folders and collections. It doesn't change Gemini Notebook's labels or Collections, or anything YouTube to NotebookLM has saved.
- Both can add buttons to the Gemini Notebook page. If something looks off, turn one off for a minute at chrome://extensions to see which it is.
- The library map and search across notebooks are free for 7 days, then need a free KastorFlow account.
- If you remove KastorFlow, your notebooks and the sources it added stay in Gemini Notebook.
Playlists as one source, frames with transcripts, and the rest of the notebook work. Free to install, no account needed to start.
Add to ChromeQuestions
What's the difference between KastorFlow and YouTube to NotebookLM?
Both send YouTube videos, playlists, channels and search results to Gemini Notebook (formerly NotebookLM). KastorFlow also merges a playlist into one source, checks the notebook has room first, captures a video's frames with its transcript, and does the rest of the notebook work: it audits sources, fills the gaps you approve, builds research notebooks from a topic, runs automations and sends flashcards to Anki.
Can I add a whole YouTube playlist to NotebookLM as one source?
Not in Gemini Notebook itself, which takes one video per link; a playlist link brings in only the page's text. KastorFlow merges a playlist or channel into one source, one for every 100 videos, so a long playlist uses one or a few of a notebook's source slots instead of one per video.
Can I add a YouTube channel to NotebookLM?
Not with the channel link: in our October 30, 2026 test Gemini Notebook refused it with "Unable to import this web page due to domain restrictions." KastorFlow adds a channel's recent uploads, up to 100 videos, each as its own source or merged into one.
Can NotebookLM read a video's slides?
Gemini Notebook imports a YouTube video's transcript only. KastorFlow's Video frames captures the video's frames and its transcript into one PDF source, so slides and on-screen text come in too.
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