perchè firefox non supporta i tag object quindi devi usare anche i tag embeded..

prova a riadattare il tuo codice html seguendo questo codice di esempio:


codice:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 
<html> 
<head> 
<title>titolo</title> 
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> 
<meta name="robots" content="ALL"> 

<style type="text/css"> 
html, body { 
width: 100%; 
height: 100%; 
margin: 0px; 
} 
table { 
width: 100%; 
height: 100%; 
} 

</style> 
</head> 
<body> 
<script language=Javascript src=flash-detect.js> 
</script> 
<script language=Javascript src=flash-detect-alert.js> 
</script> 
<table align="center" cellpadding="0" cellspacing="0"> 
<tr> 
<td align="center" valign="middle"> 

<object type="application/x-shockwave-flash" data="index.swf" width="100%" height="100%"> 
<param name="movie" value="index.swf"> 
<param name="menu" value="false"> 
</object> 

</td> 
</tr> 
</table> 

</body> 
</html>