A person who sits at the movies or in home watching a movie, and feels the need to describe every thing happening in the movie, as if they are sitting there Narrating for a blind person.
O.C.N.:
"They just entered the house, they're walking down the hallway, no sign of the bad guy yet. OMG, the bad guy just jumped out of the closet!"
Anoyed person:
"Would you stop being such an Obsessive Compulsive Narrator?! We have eyes of our own, we can see for our selves!"
The narrator is the passive voice in the story. He/She/It will usually tell the reader or viewer what is going on and other little tidbits of information the main characters don't even know about.
Some narrators in famous books, movies, stories: The Brothers Karamazov, Fight Club, The Red Death.
To inflict equal damage on yourself while attempting to harm an adversary. Much like presidential candidate Ralph Nader did to himself and Al Gore in the 2000 election.
The material that is used when the narrator won't allow you to go somewhere because it's protected by plot.
Narrator: The entrance is barred by wooden planks, the only other way is to go through this really creepy labyrinth that is filled with monsters and will advance the plot.
Character 1: Couldn't I just burn the wooden planks?
Narrator: No!
Character 2: Couldn't I just fire my laser sword and disintegrate the planks or something?
Narrator: No!
Character 1: Couldn't I just melt it with my acid crystals or run it over with my working tank or maybe just chop it in half with one of my 7 axes?
Narrator: No!
Character 1: Why not?
Narrator: Because it's protected by a layer of plot/narratorium.