He has guitar leads on his hands, and preset loops playing on each tv - for example, drum samples, tones - recorded on VHS. The audio is recorded as the video signal. Then, by putting his hands near the front of a television, the video signal is picked up by the guitar lead and played through the amplifier. He can play it by selecting which sample to play when.

Another video of him playing: http://www.youtube.com/watch?v=v5T2Q_wgoKg

And a video of his other project, Open Reel Ensemble: http://www.youtube.com/watch?v=AFM8UarAuVw