I've yet to let my monitor do the work for me. I just load the file into some kind of video player (the built-in NVidia player is passable, but has zero options), and play it that way. The program also remembers the settings for the files, so you don't have to tell it the next time you open that file, even if you've played something with a totally different format in the interim. Going into the monitor's menus, which are far from intuitive, is way too much trouble for watching video.
As for how it detects.. I have no idea. Most video streams are just video.. there's nothing except the visual to tell you that it's 3D, SBS, top/bottom, which one's left or right, etc.
Welcome to Rivendell, Mister Anderson.