Power bridges such as the one in the picture is a great way to have your wires concealed inside the wall. Many installation companies cut corners by snaking both audio/video and power cords inside the wall and connecting the power to outlets below. Some TV installation companies even run extension cords inside the wall. What these companies don't tell their clients is that its against national code to have any power cords inside your walls and if you are a home owner it will void your home owners insurance if there is ever a fire. If you want your TV mounted the right way and you want in-wall wire concealment always have a power outlet or a power bridge installed behind the TV.