There used to be a function where you paint an area with a color key - bright magenta or nasty cyan - and the graphics card would directly render decoded mpeg2

There used to be a function where you paint an area with a color key - bright magenta or nasty cyan - and the graphics card would directly render decoded mpeg2 into that region. If you moved your media player fast enough, you'd see magenta seams, as the rendering would lag one frame. At least with some cards or drivers, the area was not clipped properly, and you would see artifacts if the mask color appeared in other windows (or a window using the color was on top of the video). I think this fell out of use when people moved to the "compose everything" rendering scheme.