Okay so this is what you will typically see if you look at the back of any standard Famicom. RF Switch, a switch between whether you watch the TV or the Game (which is rendered moot by the mod), etc etc.
This is not on the side of any Famicom system, because none of the original models had AV inputs. The guy that did this did a good job of making it look tidy.
Okay this isn't technically a mod, but it takes up way less space on a power strip than the original box of an AC Adapter did.