Check your color correction settings for your video card. Adjust for overlay to your liking. It should work for both ATI and/or NVidia cards.

For NVidia, go to the Display Properties, Advanced, <insert card here>, Color Correction menu. In the Apply color changes to dropbox, select overlay. Then tweak the brightness, contrast and/or gamma. Usually increasing the gamma will do.

You can have a video running at the same time to see the results real-time.