KastorFlowUpdated November 6, 2026
The YouTube extension for NotebookLM
KastorFlow is a Chrome extension for NotebookLM, now Gemini Notebook. These are its YouTube tools, what each one does for you, and where it stops.
Gemini Notebook takes YouTube links one video at a time. A playlist link brings in no transcripts, and a channel link fails. KastorFlow fills that gap. It adds a whole playlist, a channel's recent uploads or a YouTube search, each video as its own source or merged into one source. It captures a video's frames with its transcript as a PDF, checks the notebook has room before it starts, and can repeat an import on a schedule. It doesn't change what Gemini Notebook can read: a video without captions still has no transcript.
The gap it fills
In our tests of Gemini Notebook on October 30 and November 6, 2026, single video links worked well, even a course of almost 25 hours. Everything around them was harder:
- A playlist link came in as about 700 words of page text, with no transcripts.
- A channel link failed: "Unable to import this web page due to domain restrictions."
- The same video pasted twice became two sources.
- Each video used one of the notebook's 50 free slots.
- Only the spoken words came in, never the slides or code on screen.
Each tool below answers one of those. Our full YouTube test
What each tool does for you
Save a video from YouTube itself
KastorFlow adds a NotebookLM button to YouTube: next to Subscribe on a video, below the title on a playlist page, and next to Filters on search results. Click it, pick a notebook or create a new one, and save. On a search page you also choose how many results to save. If the notebook is short of room, it says so before anything is sent: "This notebook only has 3 slots free. Reduce to 3 or fewer videos, or create a new notebook." You can also paste a single link into KastorFlow's popup, side panel or Collect page.
A whole playlist, channel or search, one source per video
Paste the address into the bar on the Collect page and click Import. The Import from YouTube window shows what it found, with titles and lengths, and you choose the notebook under Adding to.
- A playlist: up to its first 100 videos.
- A channel: its Videos tab, where YouTube shows about 30 recent uploads. You choose how many, newest first.
- A search: about 20 results, the same way.
- A video that's already in the notebook is skipped, not added twice.
A whole playlist or channel as one source
Choose One merged source instead, and the videos go into one source. Each video's title becomes a heading over its transcript, in playlist order, so the chat can still tell you which video a point came from. Up to 100 videos fit in one source, and very long transcripts are split into more than one. This is how a 40-video course fits in a free notebook using one slot instead of 40. Search results can't be merged.
Video frames: what's on screen, not just what's said
Open KastorFlow's side panel on the video's page and choose Capture video frames. You set the start time, how long to capture (up to an hour) and how many frames a second, from one every 20 seconds to two a second. The default is two minutes at one frame every three seconds. Keep keyframes only saves a frame only when at least 10% of the picture has changed, which turns a slide lecture into one picture per slide. The frames and the video's transcript go into the notebook as one PDF source.
The limits are real ones: at most 200 frames per capture, each 480 pixels wide, and a PDF of up to 50 MB (the panel shows the estimated size before you start). The video's tab has to stay in front while it captures. It works on a video in any tab, but the transcript only comes from YouTube. Right-to-left text, such as Hebrew or Arabic, doesn't come out right in the PDF yet. If the import fails, your frames wait under Saved video frames in the side panel.
Imports on a schedule
The ready-made automation Import YouTube on a schedule imports a playlist, channel or search into a notebook weekly, or as often as you set. Each run reads the list again. Automations
Plans
| Tool | Free | Pro |
|---|---|---|
| Paste a link (one video) | 10 a day | No daily limit |
| One source per video from a playlist, channel or search | 3 runs a month | No monthly limit |
| A whole playlist or channel as one source | 1 a month | 50 a month |
| Video frames with the transcript, as a PDF | 3 a month | No monthly limit |
| Imports on a schedule (automations) | Not included | Included |
| Room check before an import | Included | Included |
Plans as of November 6, 2026. Pro+ has the same YouTube limits as Pro. Every tool by plan
What it can't do
- Import a video that has no captions. KastorFlow uses Gemini Notebook's own import to read transcripts, so the same rule applies. Video frames is the way around it.
- Read private playlists or channels. You'll see "This playlist or channel is private or doesn't exist."
- Reach a channel's whole back catalogue. It sees the recent uploads YouTube shows. Use the creator's playlists for older videos.
- Raise Gemini Notebook's limits. Sources per notebook come from your Google plan. KastorFlow helps you use the room you have. Gemini Notebook's limits
- Keep working if YouTube changes its pages. If that happens it says "YouTube page structure changed" and asks you to report it. Until it's fixed, paste video links by hand.
After the import
- Send Studio flashcards straight into an Anki deck: 1 a month on Free, no monthly limit on Pro. Flashcards to Anki
- Publish Audio Overviews as your own podcast feed: 1,000 published minutes on Pro. Podcast feed
- Audit a notebook's sources and fill the gaps you approve: 1 of each a month on Free and Pro, no monthly limit on Pro+. The audit
- Tag, file and search video sources across all your notebooks in the Library. It's free; after 7 days it needs a free account. Organize
Compared feature by feature: KastorFlow vs YouTube to NotebookLM
More: NotebookLM extensions compared · Folders in NotebookLM · NotebookLM MCP · How many sources a notebook holds
Playlists, channels and frames into Gemini Notebook. Free to install, no account needed to start.
Add to ChromeQuestions
Is there a Chrome extension to add YouTube playlists to NotebookLM?
Yes. KastorFlow adds a whole playlist, a channel's recent uploads or a YouTube search to a notebook, each video as its own source or merged into one source.
Does it work with Gemini Notebook?
Yes. KastorFlow works on notebook.google.com, Gemini Notebook's address, and on notebooklm.google.com.
Is the YouTube import free?
Free includes 10 single links a day, 3 playlist, channel or search runs a month, 1 playlist merged into one source a month and 3 video-frame captures a month. Pro removes the monthly limits on runs and captures, merges up to 50 playlists a month and adds scheduled imports.
Does KastorFlow download YouTube videos?
No. It adds video links to Gemini Notebook, which imports their captions. Video frames takes pictures of the video playing in your tab and puts them in a PDF with the transcript.
Can it import a video that has no captions?
Not as a transcript, because Gemini Notebook has nothing to read. Video frames still captures what's on screen and imports it as a PDF without a transcript.
More on YouTube and Gemini Notebook: YouTube to Gemini Notebook · a whole playlist · a channel · notes and flashcards from videos · can it watch videos? · when a video won't import