I didnt watch the video but Ive seen him use it and I believe the device youre referring to is the KORG Kaoss Pad
http://http://www.korg.com/gear/info.asp?a_prod_no=KP2
EDIT: ok i just watched the video and I realize now it is not what I was thinking. But he does use the Kaoss Pad as well which is also very cool...