Although you are generally right, assertions defined for plugs have precedence. That means (if I’m right) that if opera assertion contains any information about content interfaces in its plugs, the assertion of the slot (the content snap) would not be taken into consideration. As opera is plugging chromium-ffmpeg I think we also need to explicitly allow other content snaps (even if they have global auto-connection at the slot side) in the opera declaration.
I may be wrong here, so let’s double check if the changes I made work