Jittery videos, black border lines in Chrome

I always get "Your submission can't be verified. Please try again."

So let's continue here

Here is an example I uploaded to Review 360:
https://360.articulate.com/review/content/4b7ba88b-10f3-4c8c-8c22-81b3ff12c7bc/review

Interestingly we observed that this issue doesn't show up on all machines. Strangely on some machines there are never black borders around the video but instead there are white lines above the course screen, see screenshot attached.

Puzzingly it is not possible to make a screenshot or a video capture of the black lines. Any screenshot or video capture looks fine, the black lines are not visible. Only the white lines at the top can be recorded.

EDIT: ah, those bright line come from the other video with the explosion. Both header and that video have a y position of 0, so these lines should normally also not show up.

Setting to 'Launching in a new window' and 'Resize browser to fill screen' doesn't change anything. Chrome is opening is still opening it in a tab and browser window size remains unchanged.

Best regards,
Huan