Following the details link on youtube yields what wtracy found. Looking around the site, I managed to dig this [0] up, which, judging by the filename, will be used in their Siggraph talk. Unfortunately, it is still very brief and doesn't expand much on the preview. Here's [1] the paper that it references, which does give more detail about voxel rendering.

Though I haven't looked very much into the techniques in voxel rendering, it seems animation, to this point, has been only a theoretical possibility and a huge setback. That Crassin et al. can achieve a reasonable framerate on such complex scenes struck me as a very big achievement. We'll probably have to wait a few more months for more details, though.

[0] : http://artis.imag.fr/Publications/2011/CNSGE11a/GIVoxels_Sig...

[1] : http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.158...

I found a very brief PDF here: http://artis.imag.fr/Publications/2011/CNSGE11/

If anyone finds more detailed information, I would be very interested too.