its got a virus
AVG IS PICKING THIS UP AS A TROJAN DOWNLOADER.NOT THE ONLY ONE REPORTING THIS
This script was stolen from the original script available on this site, edited to include ads, then obfuscated so you cannot modify, enhance, or fix bugs/malware within the code.
I recommend the FBMW++ script instead, which is an enhanced version of the old FBMW+ script. It does everything this script does and more. You can find that here: http://userscripts.org/scripts/show/39510