This stuff is known as Parkour, which is basically the art of moving past (above, below, through) obstacles as smoothly and seamlessly as possible.

There are some pretty crazy movies out there of people practicing this art.

http://www.youtube.com/watch?v=TF1arO9Jkb8&search=omg%20parkour (this ones absolutely crazy)
http://www.youtube.com/results?search=parkour&search_type=search_videos&search=Search (a bunch of videos)