Embedding a clip is very easy.
First you need the youtube URL.
See the part that is in bold. That is the video ID for you tube. Remove everything but the bolded text, like so
Now wrap it with the youtube tag like so.
PHP Code:
[youtube]TnyT44GeNgk[/youtube]
Note if you go to the advance editor you can just highlight the youtube video and press the youtube icon and it will automatically tag the video