How can I reproduce the MatchMoving/MotionTracking technique from Just Dance?
The Kinect SDK has a skeletal tracking demo in the c++ api (BodyBasics). The skeleton you get is the same "topology" unless it fails to acquire the skeleton. So you can easily compare the left shoulder of two captures as you always know which point it is.

You'll have to experience with metrics. A simple point to point metric would probably be sufficient though. Maybe with some weights on different body parts though.