SlackBuildsOrg/multimedia/opera-ffmpeg-codecs

opera-ffmpeg-codecs (Extra ffmpeg codec for Opera browser)

Additional support for proprietary codecs for Opera Stable.

This will add H.264 support to Opera Developer and not replacing the 
default /usr/lib/opera/libffmpeg.so.

For tests, go to:

 * https://html5test.com
 * https://www.youtube.com/html5
 * http://www.quirksmode.org/html5/tests/video.html