A video from the UK shows an older man in a heated road rage argument reaching into another car and grabbing the driver. A few bystanders approach the man in an attempt to calm down. One of the witnesses happens to be an undercover police officer and approaches the old man and tells him he's being place under arrested on suspicion of assault.
The old man thinks he did nothing wrong and seems like he doesn't believe the man is really a cop and starts resisting the man. The undercover cop then takes the old man to the ground and has to restrain the man who doesn't want to cooperate. Uniformed police arrive to the scene and take the man into custody.