Can confirm that this WILL work, I've used this method on my previous car.The trick is to get the actual dent really hot using the hair dryer, spray something ice cold onto the dent & watch the magic happen
It's crap when this happens. I have had a car dented and a wing mirror snapped off in a car park on two separate occasions. Good thing was the guy with the wing mirror was caught on CCTV, Police went back to him and he paid up!
That was pretty much my thoughts, surely that type of extreme temperatures can't be good for the paint. Looks and sounds impressive though.
Good luck with the dent removal if you give it a go.