If I'm reading this right, it's more likely to prevent access from outside an AVS site (the ones listed). The * would just mean www.mancheck.com, www2.mancheck.com, www99.mancheck.com all get treated the same (i.e., allowed). Anyone not coming from one of those URLs would get kicked out. AuthType Basic is generally used for password-protection via .htaccess - I don't think that will work well here, depends on your server. You also need mod_rewrite enabled for this to work.

If all you want to do is stop hotlinking, though, the htaccess you have is the wrong tool. Something like :

RewriteEngine on
RewriteCond %{HTTP_REFERER} !^$
RewriteCond %{HTTP_REFERER} !^http://domain.com/.*$ [NC]
RewriteCond %{HTTP_REFERER} !^http://www.domain.com/.*$ [NC]
RewriteRule .*\.gif$ - [L]

RewriteCond %{HTTP_REFERER} !^$
RewriteCond %{HTTP_REFERER} !^http://domain.com/.*$ [NC]
RewriteCond %{HTTP_REFERER} !^http://www.domain.com/.*$ [NC]
RewriteRule .*\.jpg$ - [L]

Should stop jpg/gif files from being hotlinked. As a side effect, though, people using security software that blocks referring URL will not be able to view images, even when they're supposed to be able to, in some cases.

-d