Some YouTube content creators split their videos into chapters. A subset of them kindly offer the list of chapters titles on description video, with their starting timestamp. Sometimes they decide not to show them.
How can I get the list of chapters titles?
Onliner to do this using youtube-dl (or maybe better yt-dlp instead) and jq JSON processor:
youtube-dl --dump-json videoIDorURL | jq --raw-output ".chapters[].title"
With a little extra magic should be possible to add the starting timestamps. To get them:
| jq --raw-output ".chapters[].start_time" | awk '{printf("%d:%02d:%02d\n",($1/60/60%24),($1/60%60),($1%60))}'
Use yt-dlp --split-chapters to download each chapter.