Comment: Truckerbaly:

Thanks for posting the entire video. I wonder if the truck lost his brakes. As a Truck driver I may be able to give some insight. Since he stopped at the top of the hill he had brakes then. If he went down the hill in the wrong gear and lost control (either because his engine brake didn't work right, he didn't use it properly,or he didn't have one.) his brakes would have became non-functional quickly.

When he stopped at the top of the hill his brakes lights (minus one) were on. When he hit the car at the bottom his brake lights were on. Yet he left no black marks on the pavement. Loaded or empty his wheels would have been capable of locking up and would have left marks on the pavement at least. This leads me to believe that the driver had a brake failure. This failure is almost certainly driver error. My opinion, he rode the brakes down the hill, and they stopped working about a quarter mile from the accident. The weight of the load accelerated the truck into the accident. Once the brakes failed the driver was along for the ride. :(