I would have to say that while the iPhone 4's lens produces a sharper video, the iPod touch's lens seems to have a wider field of view. It's a toss up, really - and I can't perceive any clear winner. In interview situations, a wider-angle view always trumps - but who doesn't like a clear-cut lines in their videos?
I wasn't able to establish clear macro shots due to the way I was holding each device (and I didn't want to skew results). It should also be noted that this video, as well as the other one, were uploaded without any amount of editing done beforehand.