Earlier quoted context omitted.
I must have missed the perfect hand tracking. Could you share where it was? All I saw was rather exaggerated movements to make things work.
The interface widgets appear to be occluded by the user's hand, with no visible artifacts even when the hand is moving quickly. That means the system has to be tracking the hand and somehow separating it from the background, with latency of much less than a single frame. EDIT: here's a particularly blatant example, around 0:17: http://i.imgur.com/8mSv8oC.jpg The user is swiping from right to left, causing their hand…
Edit: Actually, no, I don't think it's right. Modern chroma keying could probably handle this.