@sgunhouse I guess I'm dead. I've looked everywhere for the right packages to install for OpenSuse (rpm) and the video problem, but nothing. Of course /usr/lib64/opera/libffmpeg.so exists.
Since I'd installed Opera as a flatpak I should have thought it would be complete, or at least call for dependencies, but no.
Naturally it fails on MPEG-4 ASP, H.264. H.265, and Ogg/Theora support here: html5test.opensuse.org
Widevine is not found by zypper.