I love how this little bit of simple hardware, together with some smart computer programming, achieves such nice results! It's fun to watch the little adjustment animation too. 

It also makes me wonder if a constant update system could be built ... Maybe by using Phototransistors with fast reaction times, and little detection squares that flash at 60FPS. If the sensor moves out of the square the PC could then search for the new location in the close proximity, instead of having to rescan the entire picture.

Although it would look weird to have flickering lights at the edge of the screen ...