@mrgrimm I believe it is a known problem.
Even I have a thread with the same problem. I have an script to solve it, but I don't remember exactly why I was doing each step. I apply this script after any Opera update to solve the videos issue:
sudo mv /var/lib/dpkg/info/opera-stable.postinst /var/lib/dpkg/info_beto
sudo apt-get update && sudo apt-get -f install
sudo cp ~/Beto/Keepass/libffmpeg.so /usr/lib/x86_64-linux-gnu/libffmpeg_h264.so
sudo mv /usr/lib/x86_64-linux-gnu/opera/libffmpeg.so /usr/lib/x86_64-linux-gnu/opera/libffmpeg.so.orig
sudo ln -s /usr/lib/x86_64-linux-gnu/libffmpeg_h264.so /usr/lib/x86_64-linux-gnu/opera/libffmpeg.so
I already have downloaded libffmpeg_h264.so into a permanent path and copy it overwriting the new one.
You'll need to adjust it to your path, but it is 100% working.
Hope it helps.
