I have good reasons to use Opera as my default browser (I find it lighter than Firefox Quantum and Chrome/Chromium, I like its speed-dial bookmarks, as well as other features and details).
Opera browser cannot play Youtube streaming videos .
Normal (non-live) youtube videos work fine.
I know Youtube doesn't involve flash, but in order to debug this in a larger context it may prove usefull to say that the same browsers that do not play live streams in Youtube (Opera and Chromium) are also affected by a problem where they cannot play (at least) some other (probably flash) internet video streams - while Google Chrome and Firefox are not affected by neither of these problems.
Help me debug this.
I am in elementary OS Loki up-to-date, Opera 52.0.2871.40.
I have also posted this question: How to tell if an internet video is flash or html5 .
chromium-codecs-ffmpeg-extra for the purpose of playing Vimeo videos (as indicated here) solved for Chromium all the problems I had with both Opera and Chromium (not playing live streams and a lot of other non-live online video): but not for Opera.