I love it. I really do!
But there are a few things I spot that could be improved upon.

The extremely rough edit there sort of addresses one of them - that when you run, the torso twists a bit, most noticeable at the shoulders.
What I didn't show, is that the gut and chest should also move in tandem, and his hips should twist/move opposite the shoulders.
edit -
Actually I see now that you did do -some- of that but I feel like the shoulder/chest/gut/hips movements should be more pronounced.