Well, i never used them. Why not use for optimal settings the overlay color control, what come with your GFX driver? On both nVidia and ATI cards it worked for me - well, except that Catalyst 3.4 and bellow don't remember my settings for all overlays, only for YUV420, so YUV422 are too dark...
...luckily i don't using ATI crap anymore, so...
But into 3.5 or 3.6 its fixed, IIRC