Certainly a grey area, but I would suspect that the person that loads copyright music on to Youtube and the like is breaking some kind of law.
most CD.s DVDs etc have a stipulation that the material is not for public broadcast, and by putting music on an open forum you are making this available to to the public.
It could I assume also be argued that as you choose to listen to music or watch videos, that you should first check if there is any copyright infringement. How you could check I certainly don't know.
One again my suspicion is that it is similar to listening to music from a jukebox in a public place.
You choose the song, and the owner/operator pays royalties. (or they should if they want to keep legally operating)
You certainly cant expect everyone in in the venue to pay a few cents every time they hear a song or watch a video.
perhaps Andrew can speak to his contacts at the record companies and get their point of view.