For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:obechler/openSUSE_Tumbleweed/home:obechler.repo
zypper refresh
zypper install ffmpeg-4
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:obechler/15.6/home:obechler.repo
zypper refresh
zypper install ffmpeg-4
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:obechler/15.5/home:obechler.repo
zypper refresh
zypper install ffmpeg-4