Holy fuck... Dude was playing angry birds with Chop Sticks and using a pen to write on the screen from a foot away!
I've never been so impressed with an input device before. Excepting only for the fact that yeah, it does take serious shoulder muscles to use it for long periods of time, this is truly evolutionary, making the Kinect look like a limited concept.
About the shoulder muscles thing, no one said you can't have your elbow on your desk though when doing all of this. With the Kinect I didn't feel that was possible, because it was looking for bigger motions... But this thing lets you write with a pen from a distance! It'll surely let you keep your elbows on your desktop or armrests to do certain tasks.
This is the future of the mouse, boys... It WILL be built into every laptop and monitor in 2013 and beyond, count on it!