Hey vemunddh,
Just made a screen grab of this moment. It was 1080p material. But colour grading was needed to make it look like this ;-)

 Cool! i find its better to screengrab when the FPS is high, haven't tried with 4k video yet might work aswell

 It Depends. If it is Bright outside the the exposure time for each frame is quite short 1/1000s. If it is short than every screen capture is sharp. If it is cloudy, the frame can get quite blury (1/30)s also with high frame rates. Without changing the frame rate.

 Good point! I might try messing around with some protune settings, cbf fiddling with it every time i use it