Scott McCloud has posted an example of an animated comic, Vincent Giard's bol, that works pretty well, along with a brief explanation of how motion comics can work:

The best way I’ve come up with to explain it is that looping animation (and sound, for that matter) still communicate a static span of time. If panel 2 clearly comes after panel 1 and before panel 3, it still feels like comics, even if panel 2 is a short loop of some sort.

It's a good point, and in this case, the motion gets more and then less pronounced as the comic goes along, so there is a progression to it. Scott says,

The point isn’t whether or not we want to give it a particular label or not, but whether a given comic works as storytelling. Does it feel whole? Can we lose ourselves in the reality of the strip? And in this case, I’d say yes.

I agree that the animation fits the story, but looking a the comic as a whole is a bit like trying to read a comic printed on a bowl of Jell-O.