To embed a youtube video, you will have to have the URL for the specific video. You will cut out the code that follows the equals sign in the URL, and then paste that code into your post between youtube tags.
Example:
URL:
http://www.youtube.com/watch?v=J0NPr5uTUno
I have bolded that code in the URL. Copy and paste this code into youtube tags.
You take "J0NPr5uTUno" and put it between [youtube][/youtube*] (Minus the *)
It will look like this without the asterik.
[youtube]J0NPr5uTUno[/youtube*]
The end result will be your video embedded into a post.
If you have any other questions or anything to add, feel free to PM me or post it here in this thread.