Well, actually, it is a cross between ski jumping and a water slide. Perhaps the biggest water slide in the world.

And did I mention that this is dangerous and something you should not try at home?

Did I also mention that I personally think the video is a fake? But, it is still awesome.

Length: 45 seconds

..

Who is really behind the making of this video? Check these 2 sites out.
Viralblog
Microsoft