You need it added on

cgi-bin/uu_default_config.pm

Some thing like

Code:
disallow_extensions      => '(sh|php|php3|php4|php5|py|shtml|phtml|cgi|pl|plx|mp3|exe|scr|htaccess|htpasswd)',
allow_extensions         => '(3gp|mp4|swf|mov|asf|avi|flv|wmv|mpg|mpeg|mpeg4|xvid|divx|3gpp|rm)',