jellyfin-server-freebsd VS Freenas-Quicksync

On the server side, I'd actually recommend TrueNAS Core in a ZFS RAID-z2 to allow for two drive failures. https://github.com/Thefrank/jellyfin-server-freebsd/blob/main/Installation_TrueNAS_GUI.md

Look at the troubleshooting section of this guide for the plugin, it might be helpful.

I used the "Advanced" section of this guide.

I can't speak with first hand experience on the TrueNAS Core issue. But it took me 10 seconds and the first Google result to find this: https://github.com/Thefrank/jellyfin-server-freebsd

1) https://github.com/Thefrank/jellyfin-server-freebsd

Old but still largely correct instructions are here: https://github.com/kern2011/Freenas-Quicksync

I'd say you're probably thinking of this script. Also see this page if you want to set it up manually or add it to an existing jail.

ZT uses a TAP adapter for networking, and unlike TUN adapters there is no easy toggle in the jail settings to enable these, so you need to create a custom devfs ruleset. This is similar to how you would give a jail access to the GPU for hardware transcoding.

You could use a startup script to create the ruleset, as demonstrated in these instructions for setting up a Plex jail with GPU acceleration.

If you care about hardware transcoding then check out this page.

You need to go through this guide to make QuickSync work properly in FreeNAS/TrueNAS and you need a dummy dongle to make video do hardware transcoding if you don't leave the system plugged into a monitor all the time.

I don't consider my Plex something that has to be up. And it always will need the storage, so it might be a good idea to have Plex on the FreeNAS box as a plug-in. Build it with a KabyLake or newer intel cpu to take advantage of Quick Sync hardware (de)encoding https://github.com/kern2011/Freenas-Quicksync