To do a narrative voice over the player or director adds a narrative, a sort of monologue that tells the story rather than the thoughts of a character, either spoken over the action or as filler between scenes. It can also be a kind of Intro or Outro to a whole game, usually used in conjunction with a slow take-off and slow landing.
One kind of narrative voice over used in When Our Destinies Meet is the player thought, where the thoughts and ideas of the players about the scene and play is exposed in order to shine light on the moral predicaments, the power structures, and the social situation.
Utumno used excerpts from Tolkiens works, read aloud by game masters to transition from off to on (and vice versa) at the beginning and end of the larp. The vampire larp Kindred Society used one of several pre-recorded endings at the end of their final game as an outro.