Only one embeded video/audio per thread page is working because the script is buggy.
It is defining always the same id "mediaspace" for all videos and sending that variable to player. So after first video everythin else getting "This text will be replaced"
Gyaronn ids in same HTML page must be unique.
To make it work use this
Code:
<script type='text/javascript' src='video/swfobject.js'></script>
<div id='media_{param}'>This text will be replaced</div>
<script type='text/javascript'>
var so = new SWFObject('video/player.swf','mpl','470','320','9');
so.addParam('allowfullscreen','true');
so.addParam('allowscriptaccess','always');
so.addParam('wmode','opaque');
so.addVariable('file','{param}');
so.addVariable('backcolor','CCCCFF');
so.addVariable('frontcolor','000000');
so.addVariable('lightcolor','000000');
so.addVariable('screencolor','000000');
so.write('media_{param}');
</script>