Good question.
The trick with YouTube links is to only have the bare minimum part of the link.
I think in this case it's the "/" at the end which is causing the trouble. It may work in a browser, but not on the board.
Here you go:
[youtube]
[/youtube]
Sometimes YouTube links look like this:
youtube.com/watch?v=-r-UtIffUnw&feature=feedrec_grec_index
Everything after and including the "&" needs to be removed. All we need are the numbers and letters after the "=" sign that is really part of the link.
So it should look always like this:
Also, sometimes the text of your link does this and it won't work until you fix it and put all of it on the one line:
[youtube]
[/youtube]
A good idea when posting tricky things is to use the preview button and see how it all looks.
Once posted there is also sometime to edit as well.