For the AppleTV, which is my preferred Netflix hub, the steps are surprisingly simple. You would have gone through a similar process on the initial set up of your AppleTV.
How toGo into Setting>General on your Apple TV.
Scroll down and select Network, select your network to expand into the more advanced options. It is here that you will want to change the DNS setting. This number is what tells the Netflix server where you are located, by changing it the server will provide content based on where it thinks you are.
Select Manual Configure and enter the following number.
This DNS has been working for me since August of last year and is conformed working through other sources. If, however, it is not working for you check this post for additional codes (they are also posted in Primary / Secondary pairs if you are applying this mask to a different system).
After manually entering the DNS, navigate back to the General settings menu and select Restart. Once your AppleTV restarts you will be able to enjoy the catalogue of American Netflix.
And since you're in the settings moving things around, check out this post (Hidden Apple TV Features) for ways to get more out of your Apple TV.
Please note, these DNS numbers do expire from time to time. I will do my best to update them here so that you can keep your system up to date.
Updated Jan 19, 2014
You can also watch the American content on-the-go with the iOS app. Check out this post for the instructions.
If you are having problems, check this post for troubleshooting ideas.
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