XHTML 1.1 Validation using embed tags

I would love to hear some peoples opinions on this. I am not sure what to think.

I added the following to my php script,

<script type="text/javascript">
<!--
if ( navigator.appName == "Netscape" ) {
var flash = \''. $flash_embed_tags_go_here .'';
}
else {
var flash = ''. $flash_object_tags_go_here .'';
}
document.write( flash );

// -->
</script>

I am using standard embed and object tags. My pages validate in any version of xhtml from scrict to 1.1. They have validated in Moz5, Opera7, NN7, and IE6.

I don't know why they validate. I can see how they could validate if the browser is using the object tag but they also validate using embed.

I could really use some people's opinions on this. BTW, my pages won't validate in html 4.01 strict. It gives a error on both the object and embed tags.