I had installed opera with the deb
package downloadable from Opera's site and it did not load HTML 5 videos from youtube. The only solution that worked for me was to uninstall the version I had with:
sudo apt-get remove --purge opera-stable
and then installed the version from the PPA package following this other AskUbuntu post.
Adding a pointer to the opera stable sources:
sudo sh -c 'echo "deb http://deb.opera.com/opera/ stable non-free" >> /etc/apt/sources.list.d/opera.list'
Install the key:
sudo sh -c 'wget -O - http://deb.opera.com/archive.key | apt-key add -'
Fetch the new repository:
sudo apt-get update
Install latest Opera with:
sudo apt-get install opera-stable
Now Opera is able to handle HTML5 videos.
H.246
and inMSE & H.264
, but the HTML checkbox is alright.!
's for the right two with WebM, Youtube has never complained... Are opera and all the video-related packages updated? There might be an extension/add-on to try asking for different video formats, chromium has some to request H.264, and block 60FPS videos (otherwise it's forced for higher res sometimes, terrible!) but I'm not sure about Opera. Web search found some ideas, I'd might as well post an answer