Archimedes' Death Ray - Continued

This is from BBC's "Bang Goes the Theory." I've always had an interest in the Death Ray that Archimedes built, and even attempted to build my own. This guy's setup looks like some sort of parabola that faces away from the sun. I don't know how it works, but I do know that it is AWESOME! Catch the part where he melts ROCKS! The guy says that there's nothing on Earth that can withstand the temperatures created by this thing. Ummm... Speechless.