If you have kids, you'll just love watching the kids laugh their little heads off in this video.
For those who say "That's child abuse!" I say shut up -- he's playing and interacting with his kids (which sadly a LOT of parents don't do anymore) and they wouldn't be laughing if they were hurt or not having fun. Sheltering kids with no physical play only leads to messed up kids.
But the best part at the end was (I'm assuming) the older brother: "It's alright! You're supposed to bleed a little bit on the Slip 'n' Slide!"