You can view his demo here:
test - Type in any URL to see the FireFox browser.
I like the idea of the FireFox look-a-like. I think that would be a big attraction. As I stated earlier you need to modify the CSS or use frames. With transparent iFrames you could separate your browser toolbox and the website without worrying about the CSS of the website (and the CSS of the website wouldn't change your font face/type/size/etc.).