Yeah, I've seen Gadget Addict's demonstration too. I'm still not filled with confidence in them, though; even if I don't get electrocuted (in a "proper" installation), it bothers me that they have such a powerful (and compact) element, sitting against plastic, with no thermal cut-outs.
At least fan heaters make an attempt
to be fail-safe, even if not all succeed at that...
But the funniest thing, to me, is how TT kept butchering his own maths.