How to superimpose video layers using an interactive mask (xy pad or tracking)?

First of all, I have to give props to this guy Yogstar for putting out all these incredible VJ tracks and interactive Jitter patches! All his work has been incredibly entertaining, original and inspiring so I recommend you check him out after you watch the following video which I am finally attempting to replicate in my own Jitter patch:

http://vimeo.com/7978729

I think he is using a Lemur with an array of momentary buttons to trigger what rectangular segments of the dancing video are overlaid on top of the original swimming video. I am hoping that my patch will be able to take input from a variety of different controllers (kaoss pad, ipad xy from fantastick or TouchOSC, mouse pad, wireless trackpad, etc.), and I would like to have the resolution (size of the overlaid chunks) to be a changeable parameter (rows, columns). I'm still pretty new to Jitter and matrix mixing/manipulation, so if someone could scrap together the bare bones of this or give me a hint as to which objects to use to make this happen. I think with higher resolution masks, you could do some real cool interactive pieces with this if you used jit.findbounds or even a kinect to do some interesting projection mapping stuff. What do you guys think?
-G