When setting the style class attribute using dynamic embedding with SWFObject, Safari will throw a parse error and not embed your Flash file. You need to use object bracket notation instead of dot notation.
Example: foo["pantyhose"] instead of foo.pantyhose
<head>
<title></title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<script type="text/javascript" src="assets/js/swfobject.js"></script>
<script type="text/javascript">
var flashvars = {};
flashvars.event = "%2fevent_guid_1%2f";
var params = {};
var attributes = {};
attributes["class"] = "flashcontent";
attributes.id = "FlashContent";
swfobject.embedSWF("yourHappySWF.swf", "alternativeContent", "100%", "100%", "9.0.0", false, flashvars, params, attributes);
</script>
<style type="text/css" media="screen">
html, body { height:100%; }
body { margin:0; padding:0; overflow:auto; text-align:center; }
#flashcontent { display:none; }
</style>
</head>
