It's designed for firefighting. Basically much like how firefighters were stopping run away fires on oil spouts, it meant not just to soak but to disrupt fires from their source. So you need a bunch of licenses and stuff and be able to prove it to the company before they let you buy one. They are also pretty expensive.
I understand the whole licensing bit because if the two idiots in the video stood closer to the guns, there is good chance they would have caused some serious bodily harm.