Not everyone can see what you did there (it's in quotes), so -
[QUOTE]In the URL for the video just grab the part between v= and the & and enclose it in youtube tags, see below
[URL="http://www.youtube.com/watch?v=DKjx_Ri8lcs&feature=plcp"]Evan on the zip line - YouTube[/URL]
The problem is - we used to just allow full YouTube links. But too many kept putting in extra stuff, like embedded player clauses, and those broke pages right and left, so we stopped parsing those as embedded.
The [youtube] tag works, but like before, it comes with rules. I think we'll need to double check that things don't break page formatting if the rules are violated.