Steps to reproduce:
Try to summarize (or use Discuss Document) on this youtube video:
It, for me at least, will give you a "Sorry, no transcript found for this video." message:

Even though the video clearly has subtitles (although autogenerated, they're still there).
Expected behavior:
I expected that the AI tools would find the transcript that is clearly there.
Debug info:
Firefox 114.02 and Vivaldi on Arch Linux