OK…after a little more research, I’ve managed to somewhat sort this out.
Looks like Plex Transcoding requires the use of VNET when trying to run it in a jail on FreeNAS (PMS not sending transcoded files to clients - #14 by mikec_pt).
In order to get VNET to work when FreeNAS is virtualized, you need to enable promiscuous mode on the vSwitch or Port Group.
I had originally gone down this path, but I had 80% packet loss and no connectivity to Plex so I turned VNET off. Once VNET was off, all of my networking issues went away, but then playback of transcoded videos didn’t work.
I’ve since turned promiscuous mode back on my ESXi port group (and Allow Forged Packets) and I am actually getting transcoded videos to play. But I still have 60-80% packet loss. Even from my FreeNAS VM to my Jail. Both inbound and outbound.
So I guess I’ll move back to the FreeNAS side of the house and see if I can get the packet loss issue sorted out. Either that, of hope that the Plex team can update (if even possible) so the FreeNAS jail doesn’t require VNET. Not holding my breath there. 
I hope this helps anyone that tries to go down this path.
And if anyone has any thoughts on why the packet loss on the VNET NIC, I’m open to ideas.
Thanks!
