Summarise YouTube

Fetch a YouTube video's subtitles with yt-dlp, read them, and print a summary in the conversation. The user invokes this as /summarise-youtube <url>.

Process

1. Fetch the subtitles

Download the subtitle track to the scratchpad directory, skipping the video itself:

yt-dlp --skip-download --write-subs --write-auto-subs --sub-lang en --sub-format vtt \
  --convert-subs vtt -o '<scratchpad>/subs.%(ext)s' '<url>'

--write-auto-subs covers videos that have only auto-generated captions, so this works whether or not the uploader added their own. The output file lands at <scratchpad>/subs.en.vtt.

If no subtitle file is produced, the video has no English captions available. Say so and stop - there is no transcript to summarise, and guessing from the title is not a summary.