Look at the date of that video - I've been to FeF just last October, and they definitely didn't use this there (then).

BTW, product safety hasn't ever been too high on the priority list with OSE, so use caution and common sense, or seek expert help before trying to do anything like this yourself.

I think you'd find that a flash heater design will end up being much more energy-efficient, too, perhaps even with a small bit of storage too.