Indeed. I'd go further and say that it's generally a good idea to make backups of all the cloud stuff you're using. The assumption that it'll always be there is fundamentally flawed. While there might well be outliers, companies who keep content archived for virtually ever, most platforms will go away at some point.

Personally I think Youtube is a likely candidate for this. They may very well just remove all "legacy" content one day. They have absolutely no idea what to do with the platform, except offer it to music companies to feast on. They're at war with the majority of their content creators, I'd be very surprised if they didn't go for the nuclear option at some point - maybe after a large legal scandal...

I agree, YouTube-Dl already has 50k stars on Github, it's certainly not obscure anymore. Although I'm not suggesting breaking the TOS if people are going to be using it to archive content then the best bet is probably to have the content archived as quickly as possible rather than trying to keep youtube-dl lowkey (ship has sailed) so as to not trigger DRM from YouTube

That's exactly what I do, I make a copy of every video I watch.