water,burn,cup,matches,battery How to Burn Water

Honestly, I have no idea what the exact science behind this is. IIRC, electrolysis ends when the current stops. With nothing to stop the hydrogen from escaping, it won't be around to be lit with the match. This is not my video, but I have tried it to make sure it works. So, it can't be something sneaking like adding vodka to the water during a camera cut.

Most likely, this is just the batteries leaking into the water, but feel free to discuss it!