Does higher-resolution display scaling improve movie quality? I just got a new Retina MacBook Pro, and I keep it at the default 1440x900 resolution setting due to not liking when everything is super-tiny. However, I was wondering, does the resolution setting make a difference when playing movies?

My thinking is that if the computer thinks it has more pixels, it should be able to display a higher-resolution video. Am I wrong, or should I make a habit of switching to the "More Space" resolution before playing movies?
It depends on the software you are using. As long as you haven't selected an upscaled resolution ("Larger Text" in the Displays preference pane), it should work just fine with any application designed for Mac within the last few years — including Quicktime, VLC, MPlayerX, etc. Simplifying a bit, these will all recognize that your screen's "pixels" are actually four pixels each, and make use of them.

However, if a program has not been optimized for use with retina screens, it may appear pixellated when the screen is set to a retina resolution.