Given that they have more convenient and personal methods of watching their favorite content, I have to guess that they don't watch the Boob Tube as much as their parents did at that age. I mean, I'm in my 60s and watch more content on YouTube in one week than I have on the CBS, NBC, ABC, and Fox networks combined (other than sports) in the last year. The only entertainment shows I watch are on the rerun subchannels over the air. Kids know even more about this than geezers like me.
YouTube makes sure that everything they carry, from the dozen MLB games they carry live, to Three Stooges clips, to ancient 1960s music videos and Shindig reruns, is properly licensed. Anything that an individual might put up there that violates copyright, unintentionally or on purpose, is removed quickly.