In line 3012 of http://svn.wikimedia.org/viewvc/mediawiki/trunk/phase3/languages/messages/MessagesEn.php please change to:
'isimage' => 'file link',
as, for Wikimedia Commons and other wiki websites, it is more accurate to describe videos and audios as "files" rather than "images".
Version: unspecified
Severity: minor
URL: http://www.mediawiki.org/wiki/MediaWiki:Isimage