I was missing one piece on my Mac mini, and that was having roomie start the correct application (such as Plex). This can be accomplished using roomies URL feature and Remote Buddy. Using wireshark, I figured out the urls to send. The following sequence selects Plex and then activates the behavior:
Replace the server.local name with your servers name or ip address. The offset is the menu item. Since everybody’s Remote Buddy menu items are different, you’ll have to tailor that to your particular config.