Thanks for answering :)
I tried in the example, and all I see after inserting the video is a black square and I can't play the video.
The embed code I use is:
<iframe title="YouTube video player" width="480" height="390" src="http://www.youtube.com/embed/TU_4WDtfCis" frameborder="0" allowfullscreen></iframe>
Can you tell me if it works for you?