It's weird how scrolling forward from your right to your left is more easily detected than scrolling backwards from your left to your right, but it's an amazing proof of concept.
Seems to depend on proper skin detection, which can work out of the box if the light is right. Au contraire js-aruco needs preparation, but has some nice 3D capabilities.
I really don't get the comparison to Kinect at the beginning, since this is _just_ a simple motion detector and the only fun thing is the execution environment.
Hopefully someone finds a financial incentive to pursue that venture. Maybe there's a Duolingo-like idea waiting to be taken advantage of.