I think that he's lying. I mean, hoe could you possibly start a fire with a drop of water? He's got to be hiding something.
Yep he is hiding plenty. In this case he forgot to mention that you also need a piece of glass, steady hands and a boatload of free time.
He is talking something which is possible yet extemely difficult and then he is exaggerating it to make it seem like something spectacular. He is almost certainly referring to the technique involving using a drop of water on a piece of glass to magnify sunlight and thus start a fire in the same way one would do with a magnifying lens. Yes, sure, it can be done but (a) it requires more than "just a drop of water" and (b) it's not simple by any means (though possible) to get a "drop" of water to sit perfectly on a piece of glass for the purpose of magnifying sunlight and starting a fire.
A lot of what is on that site are not necessarily outright lies but rather extremely gross exaggerations. I believe he also said something about starting a fire with a chocolate bar. Most of us here know how this one is done. Most of us also know it is at best extremely difficult to accomplish.