You can now embed YouTube videos into posts, all you need is the video code, not the whole link.

For instance, if you have http://www.youtube.com/watch?v=e-Pi6zva5wk , then all you need is the code after the "=" sign which is "e-Pi6zva5wk"


Once you have that just use the BB tags
PHP Code:
 [YT]e-Pi6zva5wk[/YT