Also a butt crack.
David Keitel, the fan who posted the video, said he started filming as soon as he came across the incident during yesterday's Cowboys-Chiefs game, so he has no idea what precipitated the arrest.
Police told KMBC-TV that they were called to respond to an unruly fan.
Police said the man then kicked an officer in the groin, severely injuring the officer. Another officer was also injured by the man, suffering lacerations to the head, arms and knees, police said.
Update: The Kansas City Star has more on the arrest, and a mug shot of the accused.