I would be very surprised if that video wasn't computer generated.. Mythbusters had a show here a while back testing if this stunt was possible..
They showed that it was possible but not with the slide length these guys had... Then as they were half way through the show the people that created this video told Mythbusters that this video was in fact computer generated... Tell me this doesn't look very real..!!
http://www.youtube.com/watch?v=w4vW3fsJ8pk Mythbusters show on it
http://www.youtube.com/watch?v=2V1BhagVjF0&feature=related This still looks very fun to try..!!!! Maybe Cactus could build one and make an amusement park.. Call it ( Cactus Land..!!! )
RC