I had the same problem. Gave up on the advice for installing the certificate and did it over USB following these instructions instead, which really was as simple as getting to that point in the instructions, unplugging HDMI, plugging in micro USB, and installing the profile.
https://langui.sh/2013/08/27/appletv-ssl-plexconnect/
then after restarting the apple tv the trailers app worked as expected.
Thanks for the suggestion - I followed the instructions and used the Apple Configurator to get the cert installed but unfortunately, still no joy... :(
When I try running the trailer application, I get the famous spinning wheel with the message 'Accessing Trailers' and it just sits there. I believe the Plex Server is running just fine and have provided the log below showing the status once executed. I have set the AppleTV DNS to the same IP as the IP_self which is the static IP that the Plex Server is running on. The AppleTV router IP is set to 192.168.1.1 which I assume is what it should be.
I am once again lost for ideas here - I have followed the instructions to the letter, but just don't know what I am missing. Could it be an issue with port forwarding? Are there certain ports that I need to open which I may not be aware of? I know things work on 443 and 80 just fine. The Plex Server app works fine from what I can tell. I can access other content just fine on the AppleTV like PBS, Disney, YouTube etc.
Also, any ideas on what one does with the third file 'trailers.key' that gets created as part of the cert generation? Does that simply live on the desktop on the Mac running Plex Server or do I need to copy somewhere? Please advise as there are no instructions for that particular file.
Again, any help would be greatly appreciated here as I feel I am another step closer, but something is just not set correct...somewhere....
22:41:26 PlexConnect: ***
22:41:26 PlexConnect: PlexConnect
22:41:26 PlexConnect: Press CTRL-C to shut down.
22:41:26 PlexConnect: ***
22:41:26 PlexConnect: started: 22:41:26
22:41:26 PlexConnect: Version: 0.3.1+
22:41:26 PlexConnect: Python: 2.7.5 (default, Mar 9 2014, 22:15:05)
[GCC 4.2.1 Compatible Apple LLVM 5.0 (clang-500.0.68)]
22:41:26 PlexConnect: Host OS: darwin
22:41:26 PlexConnect: IP_self: 192.168.1.30
22:41:26 DNSServer: started: 22:41:26
22:41:26 DNSServer: ***
22:41:26 DNSServer: DNSServer: Serving DNS on 192.168.1.30 port 53.
22:41:26 DNSServer: intercept: ['trailers.apple.com'] => 192.168.1.30
22:41:26 DNSServer: restrain: ['mesu.apple.com', 'appldnld.apple.com', 'appldnld.apple.com.edgesuite.net'] => 127.0.0.1
22:41:26 DNSServer: forward other to higher level DNS: 8.8.8.8
22:41:26 DNSServer: ***
22:41:26 WebServer: started: 22:41:26
22:41:26 WebServer: ***
22:41:26 WebServer: WebServer: Serving HTTP on 192.168.1.30 port 80.
22:41:26 WebServer: ***
22:41:26 WebServer: started: 22:41:26
22:41:26 WebServer: ***
22:41:26 WebServer: WebServer: Serving HTTPS on 192.168.1.30 port 443.