Did you watch that episode where Dean ran and climbed walls and stuff and dodged bullets? I don't remember what it was, but they were hiding behind a car and Dean just ran lol. After that he said 'What can I say, I'm a badass.' lol. Remember?
Well they called in a stunt double, since the jumping and all that was hard and for professionals, and when the stunt double did it, Jensen tried it himself and did a hell lot better lol!