The circle under the TV is the TV link. That is the TV in the bedroom, and that allows me to change the channel on the Sky box which is located in the lounge.

If I change the power cable, I can either just chop the TV end off it and wire in the new power connector, or remove the TV, remove the power switch (at the bottom of the wall), attach one cable to the other, and pull the new one through without plug.

Going sideways across plasterboard, you may have to contend with uprights. In that case, you can cut a small notch out to allow the cable past, or drill a hole through the centre of the beam.

All my cables disappear behind a small hole in the wall, and go their separate ways from there.