Try adding &wmode=transparentat the end of your YouTube URLs. See if that helps.
** change:
?wmode=transparent &wmode=transparent ( url / '?'). , jQuery:
<script>
$(document).ready(function(){
$('iframe').each(function(){
var url = $(this).attr("src");
if(url.indexOf("?")>0){
$(this).attr("src",url+"&wmode=transparent")
}else{
$(this).attr("src",url+"?wmode=transparent")
}
});
});
</script>
NB: jQuery script - , -: http://www.scorchsoft.com/news/youtube-z-index-embed-iframe-fix