[on Windows 10 Pro (Build 19042), NVIDIA GEFORCE Game Ready Driver 461.72, VRChat Build 1056]

Had been trying to work out why AVProVideo media sources within VRChat was not functioning, and I think I might have identified a cause of the problem.

So, I had been adjusting settings in NVIDIA's control panel so that VRChat wasn't running too hard unnecessarily (only have 60Hz monitors so it doesn't make sense to have VRC running higher than that), having limited framerate to 61FPS and VSync set to Fast, and any AVProVideo media source in SDK3 worlds appeared to stop working straight away with the following error:

ERROR: [AVProVideo] Error: Loading Failed. File not found, codec not supported, video resolution too high or insufficient system resources.

When I threw DDU at my GPU driver then reinstalled it, everything started working fine again, but as soon as I enabled my settings again, the player stops working. It seems to only be affected when VSync setting is set to Fast, Normal and Adaptive VSync is unaffected.

Edit: The above problem was not present in VRChat cliend build 1054, it appears that it may have been introduced in this build.