Pull the subtitles with youtube-dl, then either read it (should be much faster than watching it) or throw some typical auto-summary software at it first.

Something like: `youtube-dl --skip-download --write-sub --write-auto-sub --sub-lang=en 'https://www.youtube.com/watch?v=Tnu_Ws7Llo4'`

You can use ffmpeg to convert subtitle files between different formats. SRT is easy to clean up for reading with a a few editor macros.