Trance Video Element

I’m trying to put together a video to project behind me while I play, but one element has proved nearly impossible to find. I’m looking for clips or video of a girl dancing but it has to have a completely white background. She/they should be the only thing on the screen. Almost like what you see in mac commercials all the time. The more professional the better.

If anyone knows where the internet is hiding these gems or at least what this technique of shot is called that would be absolutely perfect.