Serves him right.
Where there's a will there's a way, and the same goes for those trying to be the ultimate asshole driver. Last week we brought you a video showing a Camaro driver trying to pass a couple of trucks because he was an impatient dick. And now there's this guy. With his trailer in tow, he actually had the balls to cut off the truck from where this dash cam video was taken. There was nothing the truck driver could do to avoid a crash, but it was the station wagon-trailer driver who paid severely. And rightly so.
There wasn't any reason to cut the truck driver off, regardless of whether or not he was driving slowly. The lesson to be learned here? Don't cut off vehicles that are bigger than the one you're driving; you're going to lose.