My guess is that they skipped the 3D step entirely, and made this demo with four 2D images (front, back, left side, right side) cleverly manipulated with meshes.
For use-case, perhaps this would be logical in a situation where game engine can only support 2D graphics, but developers still wanted some 3D look, and also wanted to be able to manipulate the graphics through bones (for efficiency) instead of rendering out a million sprite sheet frames directly from a 3D program?
Regardless of potential practicality, it's a super impressive demo!
