On Mac, the deinterlacer is turned off by default. This means that DVDs are loaded with interlacing artifacts until I dig through some pretty advanced menus and flip a few switches.
May I suggest turning on OpenGL output, and selecting the deinterlacing filter by default? Macs have a pretty stable hardware configuration, so unlike PCs and Linux boxes, you don't need to worry about working with "some random video card" and "some random driver."