Joe Simon (a widely popular BMX video editor) was sued this year because he used an unlicensed song in a wedding video that went viral. Be careful with the music you choose...
http://daredreamermag.com/2011/12/07/the-music-licensing-chickens-have-come-home-to-roost-in-wedding-and-event-videography/
"But I will say that using music illegally is like playing russian roulette, maybe you will get sued, maybe not. I just want everyone to know that the threat is real and you have to make the choice to run the gauntlet or be in the clear."