What I really want is all my subscriptions to get auto-downloaded into Plex. And for Plex to have better library management tools from the player, so I can delete after watching or move to a category.
Then show me all the algorithmic stuff when I'm on the website so I can find better stuff to subscribe to.
I was actually looking at building a script like this. Have you found anything that does it already? If not, I was just going to make a small python script with readonly access to my Youtube account that pulls down my Watch Later video IDs and feeds them to youtube-dl on my NAS. Sounds like a fun Christmas vacation project.
There are multiple articles automating this task using youtube-dl. There's also a recent project called tubesync[0] that provides a GUI and advertises itself as the sonarr/radarr for Youtube