Hi there. I ran into a major issue playing videos in Opera GX on Ubuntu (.deb). Sites like YouTube and a national TV channel were giving me an error saying, "Your browser is not compatible with video playback." I knew it was the browser because it worked fine in others (Firefox and Chrome). I tried everything without success—I even nearly broke my system trying to reinstall shared codecs (I narrowly avoided disaster by force-shutting down the PC just in time). My solution was to download a custom libffmpeg.so file from GitHub and replace the existing one in the Opera GX files using a file manager opened as root via the terminal (in my case, the location was /usr/lib/x86_64-linux-gnu/opera-gx-stable/). I hope the Opera GX team can fix this in the next Linux update; while I managed to solve it myself, there are users with less technical knowledge who might struggle, which is why I’m bringing this up. In the meantime, anyone facing the same problem can use the method I described to fix it.
For my setup, I used a file from this repository (make sure to download the version matching your architecture, usually x64): https://github.com/nwjs-ffmpeg-prebuilt/nwjs-ffmpeg-prebuilt/releases