It's too bad you can't see any license plates. I would almost swear that this happened on U.S. Highway 550 between Ouray, Colorado and Durango, Colorado. The rocks and the trees fit that part of the state, and stuff like this happens all too often on that highway. But there are lots of roads in the U.S. that have drop-offs like that.
Whereever it happened, it's a good thing the guy in the truck has help. Steve is right. It's too late to look for a commode. The driver probably slid off his seat BEFORE the truck went over the edge.
Okay, what have we learned from this little episode?
CHECK YOUR CHAINS AND YOUR BRAKES!