Hey,
I recently had to write a cross-browser and XHTML Valid code, that embeds Flash content. Well, this is a very discused issue, and found a very simple solution to it 
via (http://robertnyman.com/2007/02/01/how-to-write-valid-htmlxhtml-code-to-include-flash/)
<object type="application/x-shockwave-flash" id="name" width="100%" height="40" data="http://www.example.com/path/to/flash/name.swf"> <param name="movie" value="http://www.example.com/path/to/flash/name.swf" /> <param name="quality" value="high" /> <param name="wmode" value="transparent" /> <param name="allowScriptAccess" value="sameDomain" /> </object>