Force video overlay off

[Ryom]

Is there a way to globally disable video overlay for mpeg2 video without lowering the video acceleration sliders in the display properties? I ask this because I have a custom color curve setup in my color correction options, but it doesn't apply it to overlayed video... so everything mpeg2 or overlayed video (DVDs, HD OTA via tv capture) comes out too dark if drawn via overlay. There doesn't appear to be a way to disable video overlay in either the ATI Catalyst Media Center (HD OTA) or Cyberlink PowerDVD (DVDs). I have a nvidia 6800gt and pretty recent drivers.