All you do is copy the embed code, which will look like this:
<iframe width="640" height="360" src="//www.youtube.com/embed/JPC0N0U0aco?feature=player_detailpage" frameborder="0" allowfullscreen></iframe>
Then, you back some stuff out, and make it look like this:
//www.youtube.com/embed/JPC0N0U0aco?feature=player_detailpage
Next, you make it look like this:
http://www.youtube.com/embed/JPC0N0U0aco?feature=player_detailpage
Lastly, you do this:
[youtube] http://www.youtube.com/embed/JPC0N0U0aco?feature=player_detailpage [/youtube]So then, you get this.
[youtube]http://www.youtube.com/embed/JPC0N0U0aco?feature=player_detailpage[/youtube]