Para Tumbleweed execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/home:plater/Tumbleweed/home:plater.repo
zypper refresh
zypper install ffmpeg-4
Para Factory execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/home:plater/Factory/home:plater.repo
zypper refresh
zypper install ffmpeg-4
Para 15.6 execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/home:plater/15.6/home:plater.repo
zypper refresh
zypper install ffmpeg-4