If you want your YouTube entry code to be a bit more flexible and allow EITHER the VideoID or the entire URL use the following code
User prompt hint from text editor:
Matching regex:
(|.*youtu\.be/|.*v=)([a-zA-Z0-9_-]{8,12})(|&.*)
Resulting markup:
<object width="425" height="350">
<param name="movie" value="http://www.youtube.com/v/\\2"></param>
<param name="wmode" value="transparent"></param>
<embed src="http://www.youtube.com/v/\\2"
type="application/x-shockwave-flash" wmode="transparent"
width="425" height="350">
</embed>
</object>
---
Using the above code, this video,
https://www.youtube.com/watch?v=mVmBL8B-In0can be embedded with either the full url -
or using just the video id -
[youtube]mVmBL8B-In0[/youtube]
Attached screenshot: