[Warner306]

The GTX 980 Ti doesn't have an onboard HEVC decoder. If you look at the rendering stats, the decoder queue is empty. The video is simply not being decoded fast enough to present the frames on time.

If your display doesn't support HDR passthrough, you should choose pixel shaders with HDR output unchecked.

You should also look at the display modes section in this guide because I noticed you aren't set up to match refresh rates. This will add some judder to the motion of the video. Always best to match the display refresh rate to the source frame rate if possible.