Karina Blood wrote:
I just think that there is difference between the media files that are uploaded illegaly to YouTube and those that are played on the radio stations. Will you purchase a CD if you don't like the song after you hear it on YouTube or LastFM? I can hardly believe this. As to the radio, as far as I know, they are to compensate to artists for the music they play on the air.

Yeah, that's a good point.
Also you always can understand if the song is downoaded illegally on youtube. 
Often official chanels of artists upload music on youtube, or some chanels that have a license for that (for example vevo - this is the project of youtube and some major labels but I'm not sure if artists get a compensation for that and I read that some people set up a campaign against the project because of copyright laws violation). Other sources-users upload songs illegally. (if it's not their songs of course)

By the way as for vevo...
Also I figured out that major labels started this project to attract advertisers...so this is the another proof that major labels are interested in making a profit only...