Bright video issues...

Zeba, there is no Overlay on Windows Vista (well, there is, but WMP11 doesn't even touch it). This exact issue is driving me nuts as well, I've sent a support ticket to NVIDIA and posted the problems on Microsoft community. Nobody really cares. So you really want to see your videos right, I advise you to install and use Haali Renderer or use MPC with the option that works best for you.