today I had such a flashing of other pictures during the export. Since I never had that before, I am now thinking about what the problem is and how I can fix it.
I don't understand what you are saying. What does "such a flashing of other pictures" mean?
Did you watch the video? Otherwise it's hard to understand
No video appears.
Your video is 6 second long. It is also a video of the screen taken with a camera and not a screen capture. What I see in it is your Screen is Flashing, flickering. Like some other program is trying to steal Focus and come to the front over the top of LrC
I Think the flickering comes from the other images I export. For milliseconds the exported images will flash, but I don't know why. Never had that problem before.
Does this happen if you are in the Grid View mode?
What oprions are you selecting in the Export dialog window?
You are in the Develop module. How many images are you exporting?
First thing to try is to turn off the GPU option in the LrC preferences and test.
This does not happen on my system.