I fixed it! For future reference, you don't need the embed code. Just the URL, so for this video it would look like this:
Code:
[youtube]http://www.youtube.com/watch?v=9ysyZF-DZFY[/youtube]
If you don't strip out all the referral and embed nonsense Youtube likes to append to their URLs, the (relatively stupid) text parser can't figure out where the video is.