Ramblings, rattlings, and ranting...
From the vimeo page "Thanks! We actually use LuxRender for rendering (coupled with the Blender plugin). We obtain rough estimates of geometry, including windows, and shafts are a byproduct of placing a distant source (e.g. the sun) outside the scene."If you haven't mentioned it to Ton already it would certainly be worth doing... :)
Actually, I just happened to be around when it got linked to Ton ;)