1. Press the YouTube button on the toolbar
2. This shows up: [ YOUTUBE][/YOUTUBE]
3. Look at your YouTube link, it will look something like this:
http://www.youtube.com/watch?v=cbGWgvJN1_8
4. Copy the part near the end after v=
this section is what you're after
cbGWgvJN1_8
5. Paste this between the YOUTUBE brackets
and it will look similar to this [ YOUTUBE]cbGWgvJN1_8[/YOUTUBE]
6. Press Preview Post to check it