as @jimunderscorep said, is a dev problem because they were too lazy and too miserly that they didnt update the libffmpeg.so to the latest version.
Just find / -type f -name libffmpeg.so in your system, and replace it the one that you've found with the one that is located on /usr/lib/x86_64-linux-gnu/opera
in my case, I took it from the slack installation and the size is 2.9mb vs the "original" that it size is 1.7mb