Description of problem:
When I'm playing a video or if I'm changing the time of the video (rewind or forward), I got on the entire screen a flip to black and everything go back at normal display after one second (or less).
When the video is starting and if I don't touch the timeline, the display still normal. If I change the current tab with a playing video to another one without video and I go back to the previous tab with video, the issue happened again.
It is the case with Firefox (XWayland) or Totem (Wayland).
I don't have the issue with GNOME on Xorg
I'm using Fedora Rawhide which is up to date (I have this issue for one month).
My graphical card is nVidia Quadro 1000M with nouveau driver.
The issue still here.
This bug appears to have been reported against 'rawhide' during the Fedora 28 development cycle.
Changing version to '28'.
The issue is gone.
In fact the bug wasn't fixed. My session was X.org where the issue never happened.
But, another information. This blinking arrived when I removed a file from Nautilus. I guess that is related to the Nautilus notification inside the window.