The software synthesizer in the background, Reason, is doing the heavy lifting here. But it is cool to see Android used as a MIDI controller - working over Wi-Fi, BTW. Looks like he's adjusting the velocity of four channels and then using the ball in a box deal for filter controls. Makes me miss the days on end I used to spend sitting in front of a computer, tweaking elements of my own composition until I was happy with what I... wait a minute...