The CG green screen is due to NVidia power management optimisation. There is a workaround:

1. Open NVIDIA Control Panel (right click NVIDIA icon)
2. 3D Settings -> Manage 3D Settings
3. Program Settings ( or Global Settings if you are lazy, you can skip 5）
4. Select a program to customise, find Final Fantasy X/X-2 HD Remaster (ffx.exe) in the drop-down; if you are playing X-2 then that's the one with (ffx-2.exe).
5. Scroll down to Power management mode, in the drop-down select Prefer maximum performance
6. Apply


There is no need to restart on Win10. Solution not tested on other systems.