Jack has some serious ants in his pants about starting to walk. I think he has figured it out in his mind and knows what to do, he just can't control his legs because his Jedi force is still weak. But anytime he gets the chance, he pulls up on whatever he can grab and does the little two-step shuffle. He has resigned to a little inchworm-type crawl when he has to get something (like a cell phone) that lies just outside his reach. But I think as soon as he gets his sea legs, he's going to take off running.