In the video, a person is seen pointing at a fish tank. The tank is filled with water and has a green light shining on it. The person then proceeds to point at a tube that is connected to the tank. The tube appears to be part of the filtration system for the tank. The person then points at a pump that is also connected to the tank. The pump is likely used to circulate the water in the tank. The person's actions suggest that they are explaining how the filtration and pumping systems work in the fish tank.