If the issue is only that YT might push AI-generated content into search then all you need is playlists / bookmarks.
But I generally agree that if you really want access to something in the long term, you should back it up yourself.
Yes. Hard drives are cheap (~$10/tb in bulk refurbished) and yt-dlp still works perfectly fine. Export the channels you subscribe to and back them up if you want guaranteed access to it in the future.
yes, hoard before it is put behind a paywall or removed.
[dead]
I work on a lot of projects related to vintage/obsolete technology. It's not at all uncommon for me to research something and find that all the links are broken, and the data is long gone. So developing a sense of information fragility is a useful skill, so you can get a sense of whether to save something.
Specifically about Alan Watts: There's a great podcast called 'Being in the Way' that I believe is produced by his son. One of their goals is to have a canonical & permanent archive of Watts' talks. Might be a good thing to practice your archiving skills on. :)
https://beherenownetwork.com/category/alan-watts/