Basically it 'enhances' the color profile for movies. Interestingly enough the defualt was OFF on the review sample, but set to ON with my personal unit...and obviously others as well.
I personally would recommend turning it to Off. Messing with colors/contrast/etc in real time is all well and fine, but I rather watch a movie the way the director, editor and color production engineers wanted the movie to look. YMMV