Use the url provided by youtube when you click on the Share/Embed option below the video.
If you have a YaBB forum then please note that to make this work you need to incorporate the following code in MediaCenter.pl instead of the existing youtube code.
Akso, insert an s line 35 like so: (so http becomes https) Code:
$media_url =~s~https$1:~media:~g;
It would be nice and more future proof if it were possible to simply insert the youtube embed text in between the two media. If you are perl coder and can fix this please tell me. The trouble seems to be that the existing code pulls the input text url apart, as it converted https to http before I added the extra s above.