Brilliant! Not sure I like that particular implementation (with IR), but the idea of having the whole desktop keyboard work like a giant track pad is an enticing one. Can a track pad surface be integrated into every keyboard key?
The problem with the implementation demonstrated in the video is that the gesture is recognised, and then the action happens. There is no one-to-one mapping between the gesture in progress and action on screen, so I suspect it will not feel anywhere near as nice as a trackpad or touchscreen.
Also, I'm sure someone with this tech could make use of a certain gesture that activates one-to-one style mapping for a certain period of time / until a button is pressed.