I've been in touch with both Opera and Netflix regarding this playback issue and Opera did fix the issue with Netflix with Opera Version:64.0.3417.61 on macOS 10.15
When attempting to play any video I get the following error message:
This video file cannot be played.
(Error Code: 224002)
There are no problems viewing the videos with Safari, and I am unsure if there is anything on your end which might resolve this as well.
Have a nice day