The one guy, in that hat, that kept rolling when he lands needs to work on it, otherwise when he tries bigger stuff he may seriously injure himself. It looks as if he's landing and absorbing everything with his legs, and then rolling. the idea behind rolling is to dissapate the impact energy and spread it out. When he lands he should collapse his legs while already starting the role, directly onto his shoulder. goo on youtube, watch some of the proffesionals, I believe there are even instructional videos on it.