I think Papz told me that when selecting music. It has to be a certain publisher that you can use. He said that companies like sony will have the copyright on the music that makes it unuseable in your videos. You should try independant music or music without lyrics. In fact you should try to use Puscifer, as they have some really good music and its independant, but even then you should look it up just to be sure.
Other than that, I highly recommend these maps, especially Locks. You should also see Coral Coast.