Coincidentally I threw something together this weekend that attempts to do just that. [0] It's really simple - just extracts subtitles and feeds it to ChatGPT to generate a markdown "article".
Well it's live, so you can throw a YouTube URL into it right now and get an auto generated article from GPT-3.5 in about 15 seconds. The items on the site right now are myself / others using it. Depends on the video length, but each generated article costs about $0.005 in API usage.
Edit: Ah just understood your question (coffee just kicked in). Yes, they're precomputed from when others used it. I save the generated articles in markdown format and sort by most recently generated.