I have on my notebook with Win.10 Opera as browser and recently every second Vid is felt. On YouTube in a second window on the same?

The screen is displayed in small at the bottom right. Sometimes simultaneously. It doesn't always occur. Can't figure it out. Is rather sporadic. I have a 2.5 year old PC with normal Windows 10, but I don't have Adobe Flash Player installed. Maybe that's because?! Or because I deactivated updates for Opera, what do you think?
But YouTube has long been HTML-5 … Right?

This is due to YouTube not to Opera. As far as I know, you have activated it so that you can continue watching videos despite the search function.

Just had to xen away, maybe the blocker can lock in the long run.