Presumably those only accessibly with YouTube Music or for a fee (movie rentals).
Parent commenter said:
> Sounds like the don't understand that official music and video content like rental films are DRMed
And that's what I was responding to. Not YouTube Music.
There are plenty videos with music from the original distributors, like those I linked above, on regular YouTube, and which as mentioned will be able to download with yt-dlp.