RewriteEngine on
Options All -Indexes
RewriteBase /

RewriteCond %{HTTP_REFERER} !^$
RewriteCond %{HTTP_REFERER} !^http://(www.)?mysite.com/.*$      [NC]
RewriteCond %{HTTP_REFERER} !^http://(www.)?mysite.com$      [NC]
RewriteRule .*\.(gif|jpg|swf|flv|png)$ / [R,NC]

ErrorDocument 400     /
ErrorDocument 404     /
ErrorDocument 500     /
RewriteCond %{HTTP_HOST} ^mysite.com$
RewriteRule ^/?$ "http\:\/\/www\.mysite\.com\.au\/" [R=301,L]