Check out www.incompetech.com!
By default, these Songs are under CreativeCommons, so as long as you give credit the creator, you are allowed to use the music in your videos...
Well, Aside from being a Magician, I'm also a Musician. (Specializing in Electronic music of all sorts) I could hook you up with a custom song at no charge if you'd like. Here's some of my work: https://soundcloud.com/spadeofficial