I've seen that video before, the fellow managed to convert a beta-mag for an mp5 to fit his Glock. Furthermore, I believe the "hump" on the rear of the slide is proof that it's a converted G17 and not a true G18 - though I may be wrong on this point.
Anywho... ammunition digs into my cash flow enough as it is at a semi-auto rate of fire, I don't think I could afford to feed a pistol like that...
Although a Beretta 93R might be nice...