@ab-garcez OK. It seems to work just leaving the mouse pointer on top of the sound icon. And immediately pressing [F] key can see full screen apparently without problems. Although I have not tried it outside of youtube.
Is there no way to directly disable that animation of the icon in the browser? It catches my attention that such a silly bug has not been fixed with an update.

"Force the use of the MP4 format and the AVC codec (H.264)" in "Video codecs and formats" option is broke. Until a few days ago it was working fine, but now it is causing lag and freezing in the videos.

Essential. It greatly expands the options to install Chrome addons on Opera. These work as if were native.

@ab-garcez OK. It seems to work just leaving the mouse pointer on top of the sound icon. And immediately pressing [F] key can see full screen apparently without problems. Although I have not tried it outside of youtube.
Is there no way to directly disable that animation of the icon in the browser? It catches my attention that such a silly bug has not been fixed with an update.

The videos worked fine with "Install Chrome Extensions + h264ify" extensions for 1080p60fps. Now everything is scary lag with videos, even at 480p it suffers lag and intermittent pauses, even without those extensions. I have to use another browser to watch videos. Opera is becoming unbearable for this reason. I was not going to incorporate native h264 in version 65?