Os dejo este enlace en el que explico como solucionar los problemas de reproducción de algunos videos en html 5

https://forums.opera.com/topic/12193/how-to-fix-video-playback-problems-with-opera-32-on-linux-tutorial/1

Check my tutorial for fix video playback problems

https://forums.opera.com/topic/12193/how-to-fix-video-playback-problems-with-opera-32-on-linux-tutorial/1

Many persons reports this problem with Opera 32 on Linux systems. For flash video playback solution is easy, you must install Pepper Flash Player.

But to fix HTML 5 video playback problems solution is a bit more complicate. The problem is that Opera doesn't support H.264/MP4 codec natively. For fix it we going to use codecs of Chromium.
Now I going to enumerate the steps you must do to fix this problem:

1. You must have installed Chromium on your system.

2. Download Chromium

3. Now you must run the following command in Linux Shell: sudo ln -s /usr/lib/chromium-browser/libs/libffmpeg.so /usr/lib/x86_64-linux-gnu/opera/lib_extra/libffmpeg.so.32 (this command link Chromium libffmpeg.so file to Opera)

4. Now restart Opera and visit this site to check that HTML 5 playback work correctly.

That's it, I hope you have been helpful to them.

Source: https://gist.github.com/lukaszzek/ec04d5c953226c062dac#gistcomment-1579954