Any chance to get g-sync working in windowed mode? Gsync officially supports windowed mode applications so it should work with MadVR too.
It is really disappointing to spend $1k on a monitor and not be able to take advantage of this feature.
Note: On my system, Gsync does work in full screen exclusive mode, but only with DX11 disabled under Rendering - General Settings. But it doesn't work for all video files. Strangely it does work for all youtube videos I've tested so far (piped by SVPTube).