
This mod will modify all URLs in vBulletin's threads/posts. I haven't tested this with vbAdvanced, but there it should only work with pages that are in 'BBCode Mode' (can't recall the exact verbiage).
Regarding the format for the domains, you shouldn't specify the
http://, and you should list one domain per line. E.g.:
www.mydomain.com
forums.mydomain.com
Thanks.