youtube tags, you copy the ID from the youtube URL
like this URL for example
youtube.com/watch?v=hvBsj2-TidA
you take the ID, which i have bolded, and past it inbetween the YouTube BBCode tags
like this
[YouTube]hvBsj2-TidA[/YouTube]
and this is the result:
[youtube:3dv05qdi]hvBsj2-TidA[/youtube:3dv05qdi]