It's possible that they've disabled embedding on that video.
That might be, but my computer has been doing that to me a lot.
This is when you have to manually input the code for it to embed properly. Just know that different youtube accounts may use different embedding permissions settings.
Using the Johnny Football video you were trying to embed, here's what the full URL looks like:
Code:
http://www.youtube.com/watch?feature=player_embedded&v=n58bFRauLL4
What you'll want to do in this case is remove the:
Code:
feature=player_embedded&
Then manually input the rest of the URL together as follows:
Code:
http://www.youtube.com/watch?v=n58bFRauLL4
Wrap the newly modified URL with either:
OR