The problem of the videos in Opera in particular in Ubuntu, is simple to fix, you have to have the Chromium-ffmpeg snap updated. With it you will see all the videos without problems. What happens is that sometimes the snap /deb etc of opera is not updated as fast in linux as in Windows, hence the lag and therefore the videos do not work. Apart from looking if the Youtube videos work is not always the most advisable thing to do. I go directly to newspaper videos (using html5 etc) or television websites or platforms, if those work then there is no problem. You can check the browser in this web https://html5test.com there this web analyzes it and tells you if it has this codecs, by default when it happens not to be able the videos, in that web in the multimedia section and inside there video, must be marked with green check mark the codec H264, if it is not the videos not in Opera will not be seen.
In any case not to confuse you.
Have the snap or the chromium-ffmpeg package always updated (A few days ago an update came out).
Apart from Youtube, check, that you can watch videos in newspapers / online magazines as they use Html5, and also try in TV channels, which have their online version and also streaming platforms, such as Netflix and similar.
and 3) Test in each new updated version of Opera, the web
https://html5test.com that will tell you if H264 is missing.
I hope I can help everyone.
P.S.: Always be patient because they are based on the version of Chrome and usually go one behind.
