This goes in the HEAD section
<link rel="stylesheet" type="text/css" href="shadowbox/shadowbox.css">
<script type="text/javascript" src="shadowbox/shadowbox.js"></script>
<script src="Scripts/swfobject_modified.js" type="text/javascript"></script>
<script type="text/javascript">
Shadowbox.init({
language: 'en',
players: ['img', 'html', 'iframe', 'qt', 'wmp', 'swf', 'flv']
});
</script>
<script type='text/javascript' src='swfobject.js'></script>
This goes in the BODY section-
<body bgcolor="#000000">
<div id="container">
<ul id="c">
<li>a rel="shadowbox;width=800;height=500" title="Your title here" href="your_video.flv">Portfolio</li>
</div>
</body>
Basically, you link to the shadowbox javascript and css in the HEAD section.
As well as telling Shadowbox to trigger with the init.
Then in the BODY section, simply create a basic hypertext link but using the rel tag.
And make sure your permissions for the html file is correct on your web server.
Good luck. Took me quite a while to get it working too ; )