"Reacher" series star Alan Ritchson acted in self-defense during an altercation with a Tennessee neighbor, which was recorded on video, police said. Video of the incident, which TMZ first reported Sunday, appears to show Ritchson punching a man in a blue shirt in the torso while he was on the ground. The video does not show what happened before the fight. Brentwood police said they investigated the Sunday incident and determined through video and witness statements that Ritchson acted in self-defense. Representatives for Ritchson did not respond to a request for comment. Ritchson stars in Amazon's series "Reacher," which is based on the books by Lee Child. The lead character, Jack Reacher, is a former military policeman who solves crimes as a vigilante. The neighbor, Ronnie Taylor, declined to comment to NBC News on Tuesday. He told TMZ that Ritchson and his two children had been riding motorbikes around the neighborhood at a fast speed and revving the engine loudly Sunday afternoon.…