Originally Posted by Stephen Warren
Are you using VDPAU output, or Xv? (ppurka who reports the same issue is using Xv).
Can you try adjusting the brightness/contrast/saturation/hue settings in your video application? Alternatively, do this using nvidia-settings after your video player application has started running.
Yes, this is the issue. I went into Nvidia Control Settings - Contrast, Hue, and Saturation were all set to zero. Resetting them to 4096, 180, and 4096 respectively has made the video visible again. Brightness was set to zero as well, but this seems to be the median value. Thanks for the tip.
PS Looking at the previous responses, hitting the "Reset Defaults" does the same thing, only the HUE is changed to zero. Works fine now. I feel like I've put the Duh in Dummy....Oh well. I won't make the same mistake again...on to newer, bigger mistakes....;-)