Brian is watching a fabrication of "Little House on the Prairie." The satirized names betray that it's not genuine footage.
Though some of it can be seen through the open door, the inside of Roy's office is never shown. The same goes for his house: the gang gathers in his backyard on one occasion, but that's as much of the house as viewers will ever see. However, both locations--as well as his car, a purple El Camino, which is also never seen--are repeatedly described in great detail, with emphasis on Roy's gaudy and often inappropriate tastes. This episode is the first time we see inside Roy's house, and the first time we actually see his mother.
Roy's Mom Makes her only appearance in this Episode