So far I just handle it manually. I've dialed in pretty good preferences for incoming content, (for example, using regex-based whitelists and blacklists to weed out material I'm not interested in from channels that aren't already organized into appropriate playlists) and when I browse the videos directory to find something to watch I delete things that have been sitting there a while which I don't expect to get around to.

There would be a lot more work to do if I wanted to "product-ize" the tool, and periodically youtube breaks it by adding a new feature or moving something around. For personal use, though, it's very needs-suiting. The whole approach is also less of a tempting distraction than browsing youtube itself, so it's easier to manage how much time I spend watching videos. If I ever run out of content, I just go for a walk, or read a book!

I'd be curious to see it as well, sounds good/useful even in its nascent state. I have something similar-ish in that I have a makefile/script setup where all I do is dump a file of url's/playlists/people and let a cron job download updates to things on a 12 hour basis.

Then I just have a setup in plex for youtube videos and I have plethora of content to watch when I have time.

Its jarring to use "normal" youtube now and all the ads after using this setup.

Also really nice for archiving channels and/or preparing for when youtube randomly decides to throw strikes on videos and not being able to see them anymore or people setting things to private etc...

You might want to give Plex a try. As long as you use a preset pattern for folders/filenames, it can automatically load any arbitrary set of videos as "series" in the UI: https://support.plex.tv/articles/200265256-naming-home-serie...