Awesome. Very kind of you to test it yourself, and find those threads. I had found a similar thread on the geforce forums that was allaying my concerns. But this I think finally convinces me to keep this freakin' thing. Now to pay it off (I'm doing intra-family financing!).Just watched your video and recreated the same scenario on my gaming rig. Specs in sig. I also got a massive framerate dip and a jerky mouse when Gsync was enabled in Windowed mode when running Handbrake. I turned off Gsync in windowed mode, which I never use anyway, and it runs perfectly. I googled the issue, and others have experienced it too. It's more likely a bug with the Nvidia drivers than it is your monitor. Other people experienced it with other Gsync monitors. So it's not your Predator, it's a problem with windowed mode and Gsync. I'd turn off Gsync for windowed mode and not worry about it. Not sure why people are running games in a full screen window anyway...
https://www.reddit.com/r/ffxiv/comments/3o1wy4/psa_nvidia_driver_version_35850_causes_lag_with/
https://steamcommunity.com/app/377160/discussions/0/492378806388068945/
https://discuss.atom.io/t/g-sync-windowed-screen-very-slow/20696
So your Predator is fine.
Thanks again!
--H