Beakman explains that a video game is a version of a computer. He goes over all of the computer components and then to show how this all works, they do a skit. In the skit, they have to give the exact program code to Lester (aka computer) to be able to do the action they want.
Ralph visits Double Dan to get a virus that will allow him to slow down the Slaughter Race game. Double Dan shows him Arthur, a virus, and explains how Arthur works: he looks for defects in the programming and spreads it throughout the game.