Couple points about LiPo fires, for one they provide their own oxygen so because of that water has zero effect on putting them out. You have to use a fire extinguisher, though if one goes up that fast, doesn't really matter, it will be pretty much out before you can put an extinguisher on it. Also, Lithium reacts violently with water. I saw a video where someone through a chunk of pure lithium in a pond and it created a seriously massive explosion. Water is just going to speed up the reaction.
That guy got lucky on that one. They normally don't go up that fast. That looked like a 60C 3S cell which means there's a lot more energy that can be released all at once compared to a 20C single cell. I've watched a few nail piercing videos on the single cells and they don't go up that fast. Also, putting a nail through one provides the maximal area for energy to release. A minor puncture is not going to do that. Still, they go off pretty fast at best, but they don't usually explode like that, more of a fast burn.