the polygon to voxel conversion is just so artists can use existing tools like 3dmax or maya, which work on polygon models. think of the trees in their demo, the models have to come from somewhere. so realtime conversion is not needed.

as far as i can tell their voxel tech is just for non-moving objects like the landscape, buildings, etc. animated and moving actors are still rendered as polygons and blended into the scene (according to the article, this already works to a certain degree, but they weren't able to give a live demo, just a video).