As avi mentioned it's much better to use adobe-flashplugin from Partner repo.

This package provides the latest versions of Flash PPAPI and NPAPI in all supported releases. Even 12.04 LTS have the latest version.

Also the latest PPAPI that pepperflashplugin-nonfree diplays for me is:

20.0.0.228

and adobe-flashplugin package has:

20.0.0.267

They have been including those two for at least 9 months already so the pepperflashplugin-nonfree package isn't relevant in Ubuntu anymore.

https://www.reddit.com/r/Ubuntu/comments/32levk/adobeflashplugin_package_in_1504_development/

First of all this works only in Beta and Developer versions.

And then you have a very strict requirements.

http://www.opera.com/blogs/desktop/2016/01/first-opera-beta-update-2016/#comment-2457400236

Small comment about the Netflix support on Linux, it's not so straightforward to make it work. This is what you need:

• compatible widevine libraries (see /usr/lib/x86_64-linux-gnu/opera-beta/resources/widevine_config.json for search paths, version 48.x). I'm pretty sure some distros have a separate package for it with some custom installation dir, please let me know about that in comment

• ffmpeg with h264 support (e.g. chromium-codecs-ffmpeg-extra version 48.x)

• fake user agent to Chromium (--user-agent command line switch)

This version 48 is determined by chromium version our product is based on, major version mismatches sometimes work, but no guarantee.

In my opinion at least for now it's not worth the effort. Better just use Google Chrome for Netflix.

The newest release of Opera beta 33.0.1990.35 is now able to detect whether the chromium-codecs-ffmpeg-extra package is installed. When it is installed Opera can use it to provide support for some proprietary codecs for media elements, including H264 and MP3.

http://blogs.opera.com/desktop/2015/10/opera-beta-33-0-1990-35-update/

As per blog post the package must be up-to-date (45.0.2454.x and newer). Looking at Ubuntu repos it seems that all currently supported releases have that package up-to-date.

Yes of course you can create symbolic link instead of the whole copying and renaming but either way you will have to change that symlink when Opera Stable 32 releases to libffmpeg.so.32 and with every new version.

I really hope that Opera developers resolve this bug which I already reported to them a couple days ago.

I've found much simpler workaround than that guide which by the way is totally innacurate because there is no third_party/ffmpeg directory in chromium source code. At least not in Chrome/44.0.2403.107 (Opera Stable) and Chrome/45.0.2450.0 (Opera Developer) even master branch doesn't have that directory.

First you need to either install or download chromium-codecs-ffmpeg-extra package. You will find it in Ubuntu [universe] repo. Than you need to:

1. Create lib_extra directory under /usr/lib/x86_64-linux-gnu/opera/ (for Opera Stable) or /usr/lib/x86_64-linux-gnu/opera-developer/ (for Opera Developer)
2. Next copy libffmpegsumo.so from /usr/lib/chromium-browser/ to the directory created in first step
3. Now rename libffmpegsumo.so to libffmpeg.so.31 (for Opera Stable) or libffmpeg.so.32 (in case of Opera Developer)
4. Restart Opera

After that MP3 and H.264/MP4 are working for me in both Opera Stable and Opera Developer.