Copy the embed code offered under the video (you may have to click the share option first).
It looks like this (I selected the old embed code):
<object width="1280" height="720"><param name="movie" value="
https://www.youtube.com/v/lM5UANKMVkA? ... t;</param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="
https://www.youtube.com/v/lM5UANKMVkA?version=3&hl=en_US&hd=1" type="application/x-shockwave-flash" width="1280" height="720" allowscriptaccess="always" allowfullscreen="true"></embed></object>
We need this bit:
https://www.youtube.com/v/lM5UANKMVkAPut flash either side like so (don't insert the commas like I did) use this button

:
"[flash=,]"
https://www.youtube.com/v/lM5UANKMVkA"[/flash]"
And then once the parameters for Flash videos are in it displays like this:
https://www.youtube.com/v/lM5UANKMVkAEDIT:
I'll just try it with the new code offered straight off,, haven't noticed that before.
http://youtu.be/lM5UANKMVkANah did'nt work. I'll have another go at it later.