Perhaps Stief describes the licensing issue reasonably here http://www.gnutellaforums.com/showth...ight=licens%2A

About finding out what files are copyright, that's not easy. Perhaps this link might help Locating copyright info. But this 'might' only apply to the USA I don't know. How you find them for elsewhere might require some searchwork. Generally, if you hear it being played on the radio then it's probably copyright. If you can buy it in your music store/video store, then it's probably copyright. Music terms here. (ie: different types of licensing.)