Somthing wrong with your JS. Make sure the references are all correct and that the JS files are in the right spot. IE: AC_ActiveX.js and AC_RunActiveContent.js are there and the path is correct.
But to get it working again until you can figure it out, remove the <noscript></noscript> tags around the videos.
<script type="text/javascript">
AC_AX_RunContent( 'width','522','height','317','src','http://www.youtube.com/v/ZP5lc4sXWs4?fs=1&hl=en_US','type','application/x-shockwave-flash','allowscriptaccess','always','allowfullscreen','true','movie','http://www.youtube.com/v/ZP5lc4sXWs4?fs=1&hl=en_US' ); //end AC code
</script><noscript><object width="522" height="317"><param name="movie" value="http://www.youtube.com/v/ZP5lc4sXWs4?fs=1&hl=en_US"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/ZP5lc4sXWs4?fs=1&hl=en_US" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="522" height="317"></embed></object></noscript>