MuSuL - By default the script will only pull threads that your users have permission to view. If it's still pulling threads which users shouldn't have persmission to view, you most likely don't have your forum permissions set correctly. Go in your Admin CP, click on "Forum Permissions", and then double check that your private forums are set not to allow users to view threads for each usergroup that shouldn't have permission,
and that "Use custom settings" at the top is selected. I'm about 99% sure that if the permissions are set correctly that it will work fine, but someone is having that problem would like me to take a look let me know.
PKRWUD - No problem at all. Be sure to read about the permissions above and if you can't get it sorted out I'll be glad to take a look at things.
chitown - Did you read the FAQ section in the readme file?