Anyone Know How This Effect Was Created?

http://www.polarempire.com/vid/0802_FUEL_DETAILS_30.mov

So, the first time I saw this spot i really enjoyed it
and thought it was pretty straight forward. Then, the
more I watched, I started to doubt how simple it was,
and now question if a 3D software was used? I can do
the whole 3D "Kid Stays in the Pic" effect, and
understand the snow is also adding to the depth, but
some shots (The stairwell in particular) just have so
much 3D depth, its astonishing if it is really created
only using 2D elements in 3D space.


Any help appreciated.