I suspect it's because music (at least in the US) has a "mandatory licensing regime" for music, which is why it's possible for broadcast radio stations to play

I suspect it's because music (at least in the US) has a "mandatory licensing regime" for music, which is why it's possible for broadcast radio stations to play a wide variety of music. I don't think there's a corresponding legal framework for videorecordings, so each video broadcaster/streamer needs to negotiate independently with each rightsholder.