I have two separate video clips of two ballroom dancers dancing the same dance steps to the same music. I would like to play these two videos using some form of split screen, synchronised (by the music, so they're doing the same movements at the same time) so that I can compare their movements in detail.

Can I do this in windows movie maker? If not, does anyone know of some movie/video software tat doesn't cost an arm and a leg (i need my legs for dancing) that will do this?