I've spent the better part of a couple months making pepakura pieces of the Mk V and I am looking at that model and saying it IS the game model. Maybe he stuck a homemade AR in its hand and gave it some pretty skin but the body is just the game model of the chief.
I wish he would do it with Cortana - i think that would be even cooler, because if he did a little projector, like in the Pillar of Autumn's bridge, it would be full scale. Then i actually would have to make a Captain Keyes smoking-pipe...
EDIT: lol, i love G00gle, i just searched for "Cortana PePaKuRa" and it told me "Displaying 1-10 of ABOUT 163 search results" wtf? does it not know?
EDIT mk II: Does anyone have/know of the 3d files for cortana? ideally with textures? the nearest I have is miranda keyes w/o textures.
EDIT mk II:
Just imagine something that looks a little bit like this, sitting on your desktop: