If it's real they got exactly what they needed. A very memorable reminder of why they shouldn't do stuff like that.
Even if it's not, then it might keep somebody from trying it themselves.
One question though. Couldn't taking their camera like that be considered stealing? And doing so at gunpoint armed robbery?
Now for my commentary:
The idiots in the truck were clearly looking to start something, but did the other driver make things worse by giving them the finger, and responding to their yelling?
And I have to wonder, did the BMW driver know that gravel road dead ended? Was he just looking for a place without bystanders?