Would you mind posting your logs so I can have a look?
Here you go.
Try this:
1) stop PMS
2) rm -rf ~/Library/Application Support/Plex Media Server/Plug-in Support/Data/com.plexapp.plugins.amazoninstantvideo/
3) rm -rf ~/Library/Application Support/Plex Media Server/Plug-in Support/Caches/com.plexapp.plugins.amazoninstantvideo/
4) start PMS
Then it should work. :)
Well, I just downloaded the latest version of the plugin, cleared all my cache and other data, loaded the new plugin in, started PMS and Plex OS X and nothing. Still getting the same error on my Macbook Pro.
Logs are attached!
Well, it's definitely a step in the right direction since that urlSet exception went away. According to the logs it should have started playing. Do you have another device that you could test it on, perhaps iOS? I want to rule out the possibility that it's PMS and not the client.
Chris, are you running the latest Plex Client as well?
EDIT: Could you also provide Plex.log? Thanks.
Wow, I fee like an idiot. I was on Plex v0.9.5.3. I upgraded to v0.9.5.4 and it now works. Sorry to cause problems.
Please continue with the development of this awesome plugin.
No worries! I am glad we got it sorted out. You actually helped me discover and fix several bugs, and I really appreciate that. Enjoy the plugin and the features to come. :)
The plugin is now available from with the App Store. Enjoy! 
http://nine.plugins.plexapp.com/apps/com.plexapp.plugins.amazoninstantvideo
Great will that live update as you add features or should I stick to manual updates to help test and bug fix?
Also, one minor issue I have found, is that when you enter your credentials for the first time, you have to exit the plugin before it will update with your watch list and library.
You'll get updates faster if you keep the one you have now since the App Store version has to go through an approval process. It's your call. :)
I've noticed that issue as well. I see what I can come up with for that.
Thanks, I will go ahead and add the App Store version to my Media Center PC, then I will reserve my Macbook Pro for beta testing and feedback.
I also wanted to add, that I have not had luck with the plugin when accessing via iOS remotely. It works on iOS when I am on my local network, but not remotely. I can’t load my watch list or view any videos.
That's a tough one. Are you doing this over your cellular data connection? I've not yet tried this -- I don't want to burn through my 1GB cap. :)
If that's the case, do things like the Netflix channel work over the data plan? I want to instinctively point my finger at the network speeds you might be getting, both on the cellular network and your upstream connection at home.
I'll experiment with this on my iPhone since I can connect via VPN when not at home.
I have tested on cell data and remote WIFI. The cell data was 4 bars of LTE, the remote wifi was about 10 mbps, and my home uplink is great around 20 mbps up.
Well, at least we got that out of the way. :)
I will play with this tonight and see what I can find out.
I just tried steaming over the cellular network connected to my home VPN, and it worked:
Is there anything yours logs to indicate what's going on?
Installed the plugin on a ReadyNAS Pro and was able to access the channel via my iPhone and login and see all my media, when I launch a TV Show or Movie I get the following error:
Couldn’t start playback
Plex was unable to play this video
I will post logs tomorrow once I remove username and passwords
Thanks
Govnah, unfortunately your ReadyNAS Pro is not capable of transcoding/serving the flash-based streams that Amazon Instant serves up. You'll need to install a Plex Media Server on a Mac or PC server to enable this capability.
Thanks for the reply and I guess that is the downside of running on Linux based NAS. Is it specifically related to flash?
Heya Guys,  Is the latest Amazon Instant Video plugin the one in the channel store of plex?  I installed it, but nothing shows up when I launch the plugin.  I’m running a synology (linux) 412+  I’m having this problem on all clients (web, standalone on mac and android app).  On android I get the login screen.  I input my credentials on the android app, but then nothing happens.  
I’ll try to post a log when I have a chance.
Thanks.
