this isn't a ".htaccess" problem, it's "checking for valid users by referrer" problem. CCbill should be okay, I would assume. They use HTTP auth to allow access (coincidently, this ALSO goes in the .htaccess file as well), to member areas. This means the browser must send a valid UID/password *each hit* or the item will not be served up.
I would assume most paysites would not be vulnerable to this, but then again I'm surprised *ANYONE* would be so downright stupid to protect a members area via referrer checking. So I could stand corrected.
-Phil