updated to latest version of pinballx, upated nvidia drivers,,, verified all HDR settings off in windows and on monitor,,,,ASCR disabled on monitor, dynamic dimming disabled on monitor...
If I force my main display to backglass monitor, the video brigtness seems very consistent on the backglass monitor,, when I put it back to my main monitor playfield, it seems some type of monitor setting tries to kick in...looks like some kinda contrast adjustment makes the videos bright occasionally .....
Pretty sure it's just my monitor opposed to codec issue or pinballx... I don't want to mess with monitor settings too much as tables look great in VPX.
I am good closing topic again.