You would have followed them in the first place? That seems pretty dumb and pointless when you are probably just planning on putting a few dents in their car. If you'd follow someone for cutting you off (I didn't even watch that part so I don't know if they really cut the truck off) and beat them with a bat I hope you have deformed children and then get run over buy a train.
At any rate, you would have more than likely gotten shoot if you were ‘brave’ enough to take a swing. I'm guessing with as relatively calm as the guy with the gun was he knew how to handle himself and you would have been at most half way through the swing and had multiple bullets in you. Three by most training he might have went through, two center mass and one in the head. At that range he’s going to hit, and out in the middle of nowhere like that, you’ll probably die. You might have an hour with an injury like that to get to a trauma center, good luck. Even if you hit the guy quick enough so what, he's on the ground with a gun and it looks like the woman had a pistol too.
And guess what, that's called self defense (either of them shooting you). All on video to boot. Those guys should consider themselves lucky.
Just some food for thought if you ever decide to follow someone to scare them because they cut you off. You're a big guy, you never know how much you might scare them. You might scare them enough that they are fearing for their life. The guy in the BMW’s got a point when he says something like ‘You never know who you are following’.