There can be several reasons for your problem. The most likely is that the DJ’s equipment played the music at a slightly faster or slower than the equipment you are using to play the CD. Or perhaps your camera recorded at a slightly different speed than the source material.
In any case, you should be able to adjust the speed using your editing program. Sony Vegas, for example, permits change in playback speed without changing pitch; I imagine other programs do as well. You may also be able to alter the speed of the dance — i.e., of the video. However, if that doesn’t work, you may have to break up the song and try to re-sync each segment with the dance. It will take some tinkering, but you should be able to fix this.
Finally, you don’t have to show the entire dance; you can always cut away to people watching the dance. This will allow you to adjust small portions of the dance/music without the adjustments being obvious.
