Click the button to the left of "Font". If you hover over it, it says "Special BBCode". Click it.
Select "Media" from the drop-down box. Paste the URL of the YouTube video in the box labeled "Media URL". Click OK. It will paste the code for the video in your post.
Or you could just put the URL in between the [ media ] [ / media ] tags.
Edited by stancel, 19 August 2013 - 11:06 PM.