Here is another video i ran into on Youtube a few months back. It showcases Disney's Multiplane Camera which allowed for a more realistic depth of field in animations. This process was used in many famous animated movies, with Snow White and The Seven Dwarfs being the first of many. Pinnochio, Fantasia, Peter Pan and the Little Mermaid followed. It was also used in a Silly Symphonies short (which we talked about briefly in class) called The Old Mill.
So yeah just something interesting i thought you all (y'all) might want to check out.