First question: You use

--download-sections "*00:00-10:00"

as an option to download the first 10 minutes. The asterisk means the numbers are treated as a timestamp instead of looking for a chapter with that title.

Second question I don’t know.

I’d assume that “related” suggestions would still work, unless Youtube decides to break them out of spite.

You can get that experience any time by going to Trending.

You could also pour milk in your boots.

Yes I’m a bit confused as well, how are they supposed to know what to recommend if they don’t know what you’ve been watching?

Sounds like they kept a watch history anyway but in secret, and turning it off just means that the user can’t see it anymore. Exactly like back when turning off location history on Google apps just meant you couldn’t see it anymore, but Google still collected and kept the info.

Yes, I do wish it had a longer memory. It feels like only the past few days of watching has any impact on suggestions, if you’ve neglected to watch videos about a certain topic for over a week it’s basically ancient history and never comes up again. I’d love to get a varied mix of things I’ve been interested in for the past 6 months or even longer.