lazzlo

Or a quick an easy way i think, works for me
Make a .htaccess file
fill in your domain
upload it
RewriteEngine On
RewriteCond %{HTTP_REFERER} !^$
RewriteCond %{HTTP_REFERER} !^http://yoursite.com [NC]
RewriteCond %{HTTP_REFERER} !^http://www.yoursite.com [NC]
RewriteRule .*\.(gif|jpg|mpg|wmv|)$ [R,NC]

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