Some of you may have seen that the embedding of youtube videos doesn't seem to work in some cases. The fix for this is to copy the part of the URL after the v= into the youtube tags and not the full link.
Here is an example of incorrect
[you tube]http://www.youtube.com/watch?v=PJG9jRP518E[you tube]
And the correct way
[you tube]PJG9jRP518E[you tube]
This should now enable you to embed the youtube videos into your posts again.