It's the new Rockport truWALKzero (that's a cumbersome name) shoe.
The man is German performance artist Johan Lorbeer, known for his "still-life" stunts. He was aided by his team member Maren (see her on the cube below).
How does he do it? You can probably guess; his real arm is inside his clothing.
Anyway, pretty effective ambient ad, even if you do have to suspend your disbelief a bit too much.