I had the same problemin Xubuntu.. thomas-rager suggested the following on a thread for problems in twitter videos. I followed the instructions and everything is back to normal: "H.264/MP4 problem in Opera 49.0.2725.5 Ok, I had some time to play around. On Debian (amd64) based systems (Debian, Ubuntu, Mint, ect) you need to uninstall chromium-codecs-ffmpeg-extra with the command: sudo apt-get remove chromium-codecs-ffmpeg-extra You can uses this older version as replacement: https://launchpad.net/ubuntu/xenial/amd64/chromium-codecs-ffmpeg-extra/61.0.3163.100-0ubuntu0.16.04.1306 or as direct download: http://launchpadlibrarian.net/338867652/chromium-codecs-ffmpeg-extra_61.0.3163.100-0ubuntu0.16.04.1306_amd64.deb download the file and use: sudo dpkg --install chromium-codecs-ffmpeg-extra_61.0.3163.100-0ubuntu0.16.04.1306_amd64.deb to install it, or double click on the file. Afterwards completely restart Opera. If you want to prevent further updates of this package use this command (not recommended): sudo apt-mark hold chromium-codecs-ffmpeg-extra thomas-rager' suggestion. Give it a try!