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...
So your Predator is fine.