Yeah, it's the clip Michael Moore used. I remember seeing it during the film, and absolutely cracking up. In final count, the kid has a 12 gauge, a Mac (with magazine!), what looks to be a 5 inch S&W and a snubbie S&W, three derringers, some sort of small black autoloader, two Bryco/Jennings POS's, and I *think* a Browning .32/CZ .380 combo. Altogether he has one rifle, one SMG, and eight handguns, for a total of a dozen weapons shoved down his pants. IIRC, it was a video made by Garrett to advertise their metal detectors and the need for them (buy lots! install hundreds of thousands of them nationwide! don't you want to be safe?).
I kinda wonder if he didn't have like a chair behind him or something to place the Mac on, or else a hidden pair of suspenders to keep his pants from falling down.