install
https://addons.mozilla.org/en-US/firefox/addon/modify-headers/
Firefox will now ask to restart, let it and once it has, look to the top menu bar and go to Tools -> Web Developer -> Modify Headers.(OR, if you’re on a PC and running the newer Firefox that doesn’t show the menu bar by default, go to the orange Firefox tab on the top left -> Web Developer -> Modify Headers)
Either way, a separate smaller window will open and you’ll see towards the upper left a ‘Select Action’ dropdown box, click it and choose ‘Add’.
You’ll also see 3 input boxes, in the first after ‘Add’ enter “X-Forwarded-For” without the quotation marks.
In the second box enter “12.13.14.15″ without the quotation marks. No spaces and no full stop after the 15.
Leave the third box empty and click the other button with ‘Add’ to the right of it.
Ok, so now you have created the clever little filter you need, confirmed in the space below along with a green circle, all that’s left to >do is to click the tab with the funny looking smiley face that says ‘Start’.
And that’s it, you are all done.
OFFICIAL STREAM (Will work outside US if you followed above directions):
http://player.nbcsports.com/SNFPlayer.html?PID=61