Brennan and Booth are in Sweets's office getting advice from Sweets about the aggressive video of the other gamer. When Sweets gets the call from Hoggins the camera turns to face Brennan and Booth. The Gamer on the screen clearly sits back in his chair with an slightly annoyed look on his face even after the video was supposed to be paused earlier.
The scene in the game, where player character stabs the opponent is called 'kill screen' by Angela. It is actually a game ending sequence. 'Kill screen' is a technical term referring to the screen that is rendered in a way making the game impossible to beat, usually due to an error or an overlook by the programmers.
Bones inserts just one quarter in the arcade game but a two-player game starts.