Summarize YouTube videos with NotebookLM: notes and flashcards

What we made from one video

On November 6, 2026 we used a fresh notebook with one source: 3Blue1Brown's But what is a neural network?, about 18 minutes long. Then we asked Studio for two things a student would want: flashcards to test ourselves, and audio to listen to later.

Flashcards. We left every option on its default and clicked Generate. About a minute later we had 52 cards. The first one asked for the pixel size and total pixel count of an MNIST digit image, a fact the narrator says out loud. The card view has back and next buttons, a counter for cards you got wrong and right, and Good content and Bad content buttons for feedback.

Audio Overview. We chose the Brief format. It took about four minutes to make and came out 1 minute 39 seconds long. That's a summary to replay before a test, not a lecture.

Then we looked for a way to take them with us. The audio's menu has Share, Rename, Download, View prompt and sources, Open in new tab and Delete, so you can save it as a file. The flashcard set's menu had only Delete. We found no download or export for flashcards in Gemini Notebook.

Which Studio button for which job

Studio showed nine buttons on the day we tested. They all work from the same transcript, so pick by what you'll do with the result.

Studio buttons and menus seen in Gemini Notebook on November 6, 2026. Google changes them often.

Make notes and flashcards in Gemini Notebook

1. Add the video. Click Add sources, choose Websites, paste the link and click Insert. The video must be public and have captions.
2. Ask for notes in the chat. Be specific about the shape you want. The prompts below work well on lectures.
3. Make flashcards. In Studio, open the Flashcards options. Choose the number of cards (Fewer, Standard or More), the level (Easy, Medium or Hard), whether to include images, the language and which sources to use. Type a topic in the box if you only want one part of the video. Then click Generate.
4. Make audio. Audio Overview offers four formats: Deep Dive, Brief, Critique and Debate. Length can be Short, Default or Long, and there's a box to say what to focus on.

Prompts that work on videos:

• "Summarize this video in ten bullet points, most important first."
• "Write study notes: key terms with definitions, then the three arguments made."
• "What does the speaker assume I already know?"
• "List every step of the method shown, in order."

For a course, put all the lectures in one notebook. Then you can ask across them: "Where is backpropagation explained, and how does lecture 4 build on it?" Each answer cites the lecture it came from.

What goes wrong, and what to do

• The slides aren't in your notes. Gemini Notebook reads the transcript only. If the teacher points at a formula without reading it, your flashcards won't have it. Add the slides as a PDF, or capture the frames. What the transcript misses
• Names and terms come out wrong. Automatic captions have no punctuation and can mishear names. Check key terms in the cards against the video before you learn them.
• Timestamps are guesses. The transcript has no times in it. In an earlier test the chat gave a start time that was 23 minutes off. Find a quote in YouTube's own transcript panel instead.
• You can't take the flashcards with you. We found no download for them. Study them in Studio, or send them to Anki with KastorFlow (below).
• The audio isn't a podcast. You can download each Audio Overview as a file, but there is no podcast feed to subscribe to.
• Studio takes a while and uses your allowance. Our short Brief took four minutes. Every Studio output draws on your usage allowance, and Studio shows how much a generation will use before you start. Limits

A whole course, with KastorFlow

One video is easy by hand. A 40-lecture course is where the copying and the missing slides start to hurt. KastorFlow is a Chrome extension that helps at each step.

• All the lectures at once. Paste the playlist into the bar on KastorFlow's Collect page and choose each video as its own source, or the whole playlist as one source. Add a playlist
• The slides too. On the video's page, open KastorFlow's side panel and choose Capture video frames. The frames and the transcript go into the notebook as one PDF source, so your flashcards can include what was on the slides.
• Flashcards in Anki. In KastorFlow, open Organize → Artifacts, select one or more flashcard sets, then choose Send to → Send to Anki. Anki must be open on your computer with the AnkiConnect add-on. Set up Anki
• Your best prompts, one click away. Save the prompts you reuse and put one into the chat in a click. KastorFlow comes with 8 starter prompts.
• Audio as a podcast. Publish Audio Overviews to your own podcast feed, so they arrive in your podcast app. Podcast feed

One notebook per course keeps the answers on that course. How to study with NotebookLM · Compare plans

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