For Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:plater/Tumbleweed/home:plater.repo
zypper refresh
zypper install ffmpeg-4
For Factory run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:plater/Factory/home:plater.repo
zypper refresh
zypper install ffmpeg-4
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:plater/15.5/home:plater.repo
zypper refresh
zypper install ffmpeg-4
For 15.4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:plater/15.4/home:plater.repo
zypper refresh
zypper install ffmpeg-4