Seemed to me he wasnt happy about being blocked in by a slower car. He was entering the corners much faster than the WRX, and if he didnt have to brake so hard to avoid hitting it he would have sailed by it in the straights. Its the reason rules exist in professional racing (like LeMans) that slower classes must mve aside to allow faster classes of vehicles past. Trapping a much faster car behind a slower one can cause an accident...just like in the video.