I found this a couple days ago, so I tried it today. It actually works, I am just wondering how?

the comments on the video seem to be saying that it's because the water droplets float on a layer of steam so don't come into contact with the pan. I suspect it's a bit more than that... I suspect that the water not only floats on some steam but because of that it become superheated and does not boil... this can happen when there is no surface for the bubbles to form, and when a droplet is floating on the steam like that, that's exactly the case. I suspect if you used dirty water or put a grain of sand in the water droplet (froma distance!) it'd immediately boil.

If it works with tap water from a cup in a pan that's been used in any normak kitchen then there's goung to be enough dust to nucleate boiling; there's no superheating to speak of.

It's a well known effect and has been for many years

http://en.wikipedia.org/wiki/Leidenfrost_effect

 

Incidentally I have seen lots of references to the idea that you can put a wet finger into molten lead without injury because of this effect.

I have never seen anyone dumb enough to try it and I don't want to.