The tv shows belonging to this last category are watched just to keep track of the story while waiting for the occasional good episode that justifies remaining attached to a series that outrunned it's original concept, or for that one-per-episode cool computer graphic effect. They can be followed just fine by listening and looking at the screen every 5 seconds or so. In the case of movies, they usually are cheap B movies often downloaded from the internet or rented by mistake.
The key concept of this activity is multitasking, originating from the fact that:
a) one has not enough couch-time to watch tv from a sitting position
b) one lacks the determination to stay put and watch a now boring show just to see how it ends
c) one wants something to distract him from the pains of fat-burning.
See also: treadmill potato, elliptical potato.
John: I really needed to free some space on my TiVo, so i stationary bike potato'ed my way through the last season of Prison break and Heroes.
Michael: Well, time to go, i need to burn some fat.
Ryan: The office is on tonight, are you gonna watch it while you exercise?
Michael: Hey, i might be a stationary bike potato, but The office will *always* get some couch time from me.