I say no. I'm not a fan of youtubesque social networks like these, which consist only of a frame for other people to upload their work and don't contribute any new material to the community by themselves. I guess it must be really tempting to make one of these pages and let it update itself with user-generated content. If you are succesful, sell stuff and have ads you could make a living off it.
Not an artist? You can still upload any music you may find to help promote other artists.
Only if they allow you to do so... Don't encourage kids to upload material they haven't made to your site.
... You have full right and power to enter into and perform under these Terms, and have secured all third-party consents, licenses and permissions necessary to enter into and perform under these Terms, The material that you submit to our sites does not contain "samples" of any third party's sound recording or musical composition and will not infringe on any third party's copyright, patent, trademark, trade secret or other proprietary rights, rights of publicity or privacy or moral rights...
You dream. Nobody who uploads game music performances or remixes to your site will have any license or permission to do so. Maybe you'll get away with copyright infringement for a while, but if your website is succesful and makes a name you'll eventually begin receiving Cease and Desist letters left and right (since it is profit-oriented, with a shopping cart and all).
