This article assumes that you have read the FreeBSD Handbook. Specifically the chapter about jails.
To run properly, emby needs to run in a VNET jail. VNET jails have their own full network stack.
There are various ways to use and setup VNET. But if all we want is a jail that is connected to the
jail-host and is able to use the host's external interface, if_bridge(4) and epair(4) interfaces