Japanese studio WOW, led by Technical and Creative Director Nobumichi Asai, used the high-speed, 1,000 frame per second, Dyna-Flash projector developed by the Ishikawa Watanabe Laboratory in Tokyo.
The tiny glowing dots attached to the dancer’s faces allow them to be tracked in real time so that the overlays created by the projector perfectly match their movements and facial expressions. The sensors require just milliseconds to process those movements, and then warp and distort the projected images to perfectly match them, which is fast enough to hide any delays from the human eye.
See the full story here: http://sploid.gizmodo.com/dancers-instantly-swap-freaky-face-masks-using-a-face-t-1793818357