Once you find the embed code you can change it to anything you want, but just FYI here is some default youtube sizes so it stays proportionate.
W x H
425x349
480x390
640x510
960x750
or
You can use the custom sizer on youtube embed code to give you the correct size to match the opposite side you entered.
If your forums look best with a video width of 725, you would enter that in the width box, & youtube will give you the correct height.. which would be 574.
Slightly off topic, but one of you might have the answer..
Where do we change the size for the default vB video code.?
So that when people use the video button, it shows as widescreen (9:6 instead of 4:3)
Thanks