If the person driving the car where the video was filmed had reacted as quickly as the white truck (which was obviously much farther behind the dump truck), the accident might have been avoided. They might have warned the dump truck.
I’ve followed people for miles, waiting to jump out at a red light an tell them they had a dangerously low tire, or some similar hazard.
I’d go even farther and suggest that the white truck may have been from the same site the dump truck had left. It could easily been personal, as in the driver of the white truck knew the dump truck driver. I don’t know why the white truck wasn’t flashing its lights instead of honking the horn.
@SQUEEKY2 explained the dump truck driver’s error, and the driver of the white truck is doing all they can to avert the accident. The biggest fault I see is with the driver of the car that sat passively and watched.