Scoble's video is cool, but I'd like to hear Rana play an actual one-hour set with these (and live mixing of various audio tracks.) I'm a little skeptical as to whether or not it'd be really repetitive and/or possible to really rock a full set with iPad controllers unless they're controlling Ableton or some other DAW/DJ software. The lack of MIDI sync from iPad to iPad also has to be a huge pain point for any serious controllerism.
I think the ipad as a midi controller would be much more compelling. There wasn't much in the way of blending going on in the video which, for me at least, constitutes about half of what being an edm DJ is about (the other half being track selection).
I always thought it was taboo to use the default samples that came with an app, but she seems to be perfectly fine with it. I thought one of the things DJs prided themselves on was their ability to find unique samples to integrate into their shows. However, I'm guessing at this point the default sample library is pretty extensive...
She points out that it is usually taboo, but for this project she wanted to limit herself to sounds available in the app store. Don't ask me why.
Did she program it?
No, that one is the Korg app I believe. This one [1], however, does allow you to create your own OSC controllers.