How were you able to install the intel-media-va-driver-non-free?
I'm trying to get QuickSync working on OMV5 for use with Plex. After hours of research I got to stuck at trying to "apt install intel-media-va-driver-non-free". I get the error "Package 'intel-media-va-driver-non-free' has no installation candidate".
My CPU is Coffee Lake.
Did you enable the non-free repo in your APT source list?