Media pluging not working

Media pluging not working

Hi there
I'm a newbie to the jQuery media plugin. 
I've followed the instructions at  http://malsup.com/jquery/media/ but I haven't had any luck. 
I have jQuery core included from  http://ajax.googleapis.com/ajax/libs/jquery/1.4.0/jquery.min.js and I have downloaded and included the file from  http://malsup.com/jquery/media/jquery.media.js?v.92

I have the media call like this;
       <script type="text/javascript">
//Convert 'media' tags using jQuery
$('a.media').media();
//Style appropriate menu item
$('#menu_item_3').addClass('current');
</script>

I have a href tag like this; <a class="media" href="../media/video/lisdoonvarna_1.3gp">Lisdoonvarna</a>

I've viewed the source but it has not converted the a tag to a div as expected.

What am I doing wrong?

By the way I'm already using jquery successfully throughout my site. Just can't media to work?!