POV Character

I've recently been hearing and reading about the point of view character in screenplays. Now, my first assumption was that they meant protagonist. But no, the POV character is rarely the protagonist - it's the character who is telling the story, the one who wrote the memoir, or who represents the writer's perspective.

I'm having a little trouble getting my mind around how these characters function and how to develop them.

Joss Whedon refers to Serenity as "Mal's story as told by River." It's River's perspective on Mal and the other characters on the ship. Now, having pointed that out, I can see it (kinda) but I certainly didn't get that the first two times I watched the movie.

In Screenwriting is Storytelling by Kate Wright, she describes the POV character thusly:

...a character within the story who represents the writer's own point-of-view throughout the story and offers an understanding of what the story is about. The point-of-view character is crucial to the movie-making process because in order to understand the story as a movie on-screen, the audience must understand the transformation of the main character. If there is no point-of-view character who helps the audience define this transformation, the audience does not have a dramatic anchor for the story on-screen and consequently, does not know how to follow the inner emotional story.

She states that Titanic is from Rose's POV, The Fugitive uses the investigative team as a kind of Greek Chorus so they are the POV "character" along with Gerard. In Tootsie, it's Julie.

I don't know, I guess I always thought of the camera as the point of view, which guides the audience through the inner emotional as well as the outer story.

OK, I'm going to pick some movies and consider this.
Looking up on my wall at the movie posters -

Moulin Rouge! is Satine's story from Christian's POV.

Belle et la Bete - is it the Beast's story as told by Beauty? or vice verse? (I'm leaning toward the former)

Black Snake Moan - again, is it Rae's story as told by Lazarus, or vice verse? Or is it the Reverend telling the story about both of them?

Amelie - clearly Amelie' story, that's easy... and the fragile painter is clearly the POV character. He is used quite cleverly, his pointillist painting becoming more complete as the story comes together - also a nice reflection of the photo collection of the love interest - people who try to understand themselves by obsessing on images of strangers (as Amelie herself is.)

Blade Runner - Deckard's story... as told by Rachel? by the other detective? by Roy Batty? In a way, it could even be seen as Roy's story as told by Deckard. If we consider the POV character as expressing the writer's perspective on the story, then Roy seems to encompass this the best, though my instinct leans more toward the Olmos character even though his role is small.

Dead Again - Roman/Mike is definitely the protagonist. Grey Baker seems the POV character for Roman/Margaret storyline, but I have no idea who would be the POV for the present story. Pete?

Yeah, I'm nowhere near ready to use this device consciously.