It’s not a cap m8, it’s the video embedded into the page. To do this, look at the full url - http://www.youtube.com/watch?v=4YXBZo6R0BM&eurl;=. The code is the string after v= and before the &eurl;= (i.e. in this case the string is 4YXBZo6R0BM). When you are posting, simply click the <youtube> button above the message field, paste the string into the box and click Ok.