I was usig Firefox to check "graph.facebook.com/40796308305" but it was interpreting and showing the contents of a file on screen (the contents of a Json file) Then I tried with Internet Explorer and that was when I realized there was a file being opened and shown to me by Firefox. IE asked me whether to download or open the file "40796308305.js"
Interesting. I used Firefox, too, and I saw the same data that you did. Apparently, there is some redirection going on, and Firefox knows how to find, fetch, and interpret a .js file, while IE only knows how to find and fetch it.
Now, exactly how they are finding it, given that the direct request returns an error, is a mystery. The good news is that Firefox is open source, so all the source code is available, and you could hack through that to figure out how it is handling the initial 301 code. Not a trivial task, I'll assume.
Perhaps someone else knows. I'll admit I'm stumped.
I wonder, though, if the data you are after is available some other way. Or, perhaps, is not really intended for you to get at.