Comment # 10 on bug 1095545 from Andreas Stieger

Allow me to re-iterate: It would not be a simple upgrade, but the addition of
ffmpeg 4 while retaining an ffmpeg 3 with libraries. Just adding ffmpeg 4
without also changing the 3 version will cause duplicate binary packages upon
rebuild which you forget to mention.
Actually we only need to confirm this if we really want to keep in sync with
SLE. We could just as well submit a ffmpeg 4 for Leap and packagehub only while
leaving the ffmpeg 3 cli package alone.
So I still maintain my solution, if you want otherwise please submit.