I'm afraid that is the only way possible, at least for now and on profiles only. For some reason, after the last Vbulletin update, centering YT video without the WideScreen option is not available anymore.
If you want to normally Center a video on any thread you can use this, but it's yet to be implemented on profiles.
Using this
You must be registered for see images
and copy pasting the whole YT link will give you this result...
[video=youtube;JMnjZVn6b_U]http://www.youtube.com/watch?v=JMnjZVn6b_U[/VIDEO ][/center ]
Result
[video=youtube;JMnjZVn6b_U]http://www.youtube.com/watch?v=JMnjZVn6b_U[/video]
Edit: I apologize for that's as far as I can help, I VM'ed a Gmod to look at it

[/video]