Sorry guys, I have to agree with JCL. He is tailgating the BMW. The video is mounted on windshield and makes it appear more distance than actually is. You are seeing the Mazda side of the story. Look the road mile markers and you will see how close he is. And watch it in 720p full screen. YouTube - Mazdaspeed3 (Shitbox) and BMW 335i on Calaveras road

Bottom line: don't mess up with people on road. the person could be a psycho, serial killer, etc.