I would love to contribute, but sadly, the part of my brain responsible for coming up with ideas for MacFics had been shortcircuited for months and rewired along with the rest of my brain for "Project: BABY".
Well.......what the heck. Maybe I'll take a whack at it anyway:
I think Mac saw something he shouldn't have (as usual) and had just escaped by the seat of his pants from one gang of bad guys, who's hideout just so happened to be in a neighboring abandoned factory. While running and dodging bullets, he heads for the other abandoned factory we see in the comercial, loses them and starts looking for something useful to use to trap them once they figure out where he went.
There, he accidentally comes across another underground crime ring (huh, more bad guys. Imagine that!). After some snooping, he shortly discovers they're in the business of smuggling fake "official" SuperBowl merchandise out of the country and into Canada in exchange for explosives (don't ask me why...).
After both gangs come face-to-face and corner Mac in that room from the comercial, the head bad dudes have an arugument over who should get to kill him, thus instigating a massive brawl resulting in multiple nosebleeds, fractured knuckles, and a knockout or two. The conflict is only resolved once one of the head bad dudes realizes the other is his long lost cousin from Milwaukee and decides he "ain't so bad after all".
Meanwhile, during the fray, Mac has of course of been busy devising a plan to escape using some of the very explosives as a diversion of some kind (involving a fair amount of duct tape, a couple magnets, a ballpoint pen, a potato and also the bottle of moderately spicy salsa the second set of bad guys were planning to eat as they watched the SuperBowl), but they catch him just before he can set his plan into action. It's then that they finally decide to use Mac's own contraption, plus another stash of explosives Mac didn't even know about, to blow the whole building with him still in it.
So they tie Mac to the chair, take back their salsa, rig the explosives and get the heck outta Dodge.
There you have it. Outlandishly insane, improbable, and impractical and it makes no sense whatsoever. But hey, that's me