Study lecture videos with transcripts

1. Paste the lecture's YouTube link above, or pick one from the lecture library.
2. Play the video. The current sentence is highlighted, and auto-scroll (the A key) keeps it in view. Scroll away to read ahead and auto-scroll turns itself off; J jumps back to the current line.
3. Click any sentence to replay from there. ← and → step back or forward 5 seconds.
4. To get through a lecture faster, set the speed in the YouTube player's settings (the gear icon). The transcript follows whatever speed you pick.

Transcripts are split into chapters, usually with a short summary of each, shown in a sidebar next to the transcript (a list on phones). Read the summaries to see which parts of a lecture you need again, then click a chapter to jump to it. ⌘\ (Ctrl+\ on Windows) hides or shows the chapter sidebar.

To find a word or formula, use your browser's find (⌘F or Ctrl+F) on the transcript, then click the sentence it lands on.

1. On the lecture page, press Copy transcript (on a phone it's in the ⋯ menu). You get Markdown: the title, channel, a link back to the video, the chapter list, then the transcript with timestamps.
2. Paste it into ChatGPT, Claude or Gemini and ask for what you need, for example:

   Turn this lecture into study notes: one section per chapter,
   the key terms in bold, and the timestamp of each point in brackets.

   Write 20 flashcards from this lecture as "question | answer".
   Only use what the lecturer says. Add the timestamp to each answer.

3. Check anything surprising against the lecture: click the timestamp's line in the transcript to hear it.

More prompts, including summaries and quote lists, are in prompt recipes for YouTube transcripts.

Courses in the library are organised as series. A lecture page shows "lecture n of N" with links to the previous and next lecture, and [ and ] move between them. See Predictive History for the most complete course in the library.

New transcripts are built from the lecture's YouTube captions, so they're as accurate as those captions: technical terms and names are sometimes misheard, and there's no speaker labelling beyond where the captions mark a new speaker. Equations on the board aren't in the transcript. A lecture with no captions can't be transcribed yet; see when a video has no captions.