I found that the code provided by EmbedCode is rather tricky when displayed on a website. I store the addresses of my CloudObjects in a database and when I want to display them with php my code stops working after displaying the iframe (for instance when I want to display two CloudObjects). I tried to replicate that result like this:
printf("<iframe src=\"%s\" width=\"800\" height=\"600\" />", $result['tool1']);
printf("<iframe src=\"%s\" width=\"800\" height =\"600\" />",$result['tool2']);
$result['tool2'] are the strings corresponding to the address of my CloudObjects.
Nevertheless, by using the same commands and the traditional close tabs
<iframe src="..." width=800 height=600></script> it works.
I am aware that this is rather an issue with XHTML rendering but given that I tried opening my website with Safari, Chrome and Firefox, I think this might become handy for anything doing web development.