Thank you very much for your continuous help Richard!
Autolay on Desktop is way too hectic and too much, so "play on mouseover" is mandatory.
However the mobile and tablet versions still autoplayed all thumbnails perfectly normal.
Until now it has changed. Now the autoplay on mobile and tablet does not work anymore and the thumbnails also have an ugly play icon on mobile.
This now results in either: reworking the mobile sites as a workaround or the better version:
I hoped it might be possible to solve this problem by using css. Maybe something like:
Activating autoplay for thumbnails in customizer and then manually telling the desktop site via CSS to change it to "play on mouseover".
Is that possible?
I hope you understand what I mean.
Cheers!