I think your tag was broken.

I went in and fixed it. You almost got it right, but you don't include the whole URL in your tag; instead, just keep the part after the equal sign. In your case, the tag looks like this: [*youtube=SbTvuFcgl9I] because the URL is http://www.youtube.com/watch?v=SbTvuFcgl9I. (Remove the asterisk from the tag to make it work like I did in your post.)
Happy reviewing.