While I can’t imagine anyone would want to perform the feats demonstrated in this video, what you’re seeing is basically a hack that allows users to control PC programs – including Powerpoint – using the Kinect. Why? Because it’s there.
At IIT Delhi, a technologist named Ramaprasanna showed off his proof-of-concept demo using an unreleased Kinect SDK. Obviously you’re not going to get this on your Dell any time soon, but it’s interesting to see the direction Kinect on the PC could take.