http://www.greenguysboard.com/board/...em#faq_hotlink
Code:
RewriteEngine on
# leave this line in allow empty referrers, remove to disallow empty referrers
RewriteCond %{HTTP_REFERER} !^$ [NC]
RewriteCond %{HTTP_REFERER} !^http://(.*@)?([a-z0-9-]+\.)*yourdomain\.com(:[0-9]+)?(/.*)?$ [NC]
RewriteCond %{HTTP_REFERER} !^http://(.*@)?([a-z0-9-]+\.)*yourotherdomain\.com(:[0-9]+)?(/.*)?$ [NC]
RewriteCond %{HTTP_REFERER} !^http://(.*@)?1\.2\.3\.4(:[0-9]+)?(/.*)?$
RewriteRule .*\.(asf|mpg|mpeg|wmv|avi|rm|gif|jpeg|jpg|zip)$ - [NC,F,L]