In the video, Mr. Crew and Mr. Collier demonstrate the use of a gas simulation and its manipulation of various variables. They learn that an addition of gas particles increases pressure, using two different sized gas particles results in equal pressure, cutting the room in half increases pressure, while holding volume constant while increasing temperature increases pressure too. They also observed that when they keep pressure constant and cool the gas, the volume decreases. The simulation proved useful in understanding how changes in different variables affect a gas system.