As drivers we have certain responsibilities on the road. One of those responsibilities is to not run people over on purpose. Unlike the driver in this video, most of us usually adhere to that rule pretty well.
It's unclear what exactly set off this particular driver but as we see from the onboard camera with this motorcycle, something did. Or perhaps nothing did, and he's just a psycho.
As the vehicular intimidation escalates through the course of the three-and-a-half-minute video, the close calls become closer, with the car actually coming into contact with the filming biker, who fortunately manages to stay upright--though immediately after, he's nearly sandwiched between the car and a big rig.
To be fair, there's a bit of blame to lay on both sides after the first couple of minutes of video, with the bikers displaying their anger and frustration through close fly-bys of the car. They also continue to ride near the car, even chasing it, when sanity and safety would tell them to just get as far away as possible.
As the video closes, the filming motorcyclist manages to pull up next to the stopped car along the side of the highway, and promptly threatens to harm him. It's an understandable, even natural, human reaction, but it's not smart.