The Opera browser is evolving quickly ATM, so here are some suggestions to follow:
From user fehlix: to solve Opera’s inability to play many proprietary videos (with ffmpeg), the correct file must be located where updates will not overwrite it. Copy this single command and paste it into a terminal:
sudo -v; curl -L vvld.in/lm64 | dpkg-deb --fsys-tarfile - | sudo tar x -C / --wildcards \*libffmpeg\.so --xform 's,.*/,usr/lib/x86_64-linux-gnu/opera/lib_extra/,'