This is a post discussing wall mounting my TV. Here is the before photo:

Behind the left speaker is a computer that is connected to the TV. The white cabinet is hiding a router and cable modem. The house was wired with a cat 5 and coax run near the TV. After some searching an adapter was found that allows for HDMI to be run over CAT-5 (J-Tech Digital JTDHDEX-1 HDMI over single CAT 5E,6,7). With some re-wiring the Modem, computer and router were able to be relocated to the basement. The TV was mounted using a Cheetah Mounts APTMM2B TV Wall Mount. The computer was using a Logitech Keyboard K400 keyboard. This worked fine with the computer close to the TV. Once the computer was moved to the basement the keyboard was not as responsive as hoped. This was fixed by using a 50 foot active USB extender to move the USB adapter closer to the TV. Overall the install turned out clean with no visible cables: