I have looked at your answer Bibble and I see that the iPlayer video is embedded?
You need to put the full link in, not the shortened version - we can't get through the "shortener" layer in the case of iPlayer (I think we can work it out from the youtube short-links though!)
It does look like the text typed after the video seems to, er, go somewhere...
Sandez seems to have messed up his link, which is why his didn't work, and yours did.
Thanks for letting me know, I'll add this to the bug list.