Millenial, and yes, I used youtube-dl. My "Favourites" playlist on youtube is full of videos that have been deleted or that were posted by accounts that were deleted or banned. But they are still safely stored on my hard disk ;)

With time I've learnt that not even archive.org is reliable for some things so I save whatever I can. Sometimes I even take screenshots of things that I may need someday.

I've never stopped to think of that as "hoarding", but probably it is. Thank God those files don't take physical space at home, though!