It was print screen, here.Even if the video steam is a 30 Hz, it's from a camera filming a monitor right? So the image here probably represent 1/60 second.
The stream was according to Anandtech journalist https://forum.beyond3d.com/posts/1983197/ at 30 Hz.
To add more troubles to the ants nest: https://www.reddit.com/r/Amd/comments/6edd3h/amd_rx_vega_computex_pray_demo_fps/
P.S. The dimensions for the linked on previous page Phanteks Evolv Shift X: