Hello Phil,
Which camcorder did you buy/use please? And does it have an Audio-In? Or did you just use the built-in condensor-mic to pick up the audio?
So you have two monitors and you were just panning between each one periodically throughout the song?
I started a thread on Camcorders/Software last year if you wanted to take a quick look:
In the end, I did not purchase a camcorder because finding one(s) with an Audio-In all seem to be extortionately priced! But I have managed to secure CANTASIA-8 at EDUCATIONAL price so I intend to purchase this software quite soon. The guys at TechSmith really are most helpful indeed. (Though obviously you are quite happy with your Sony Vegas! 
).
I did experiment with the VIDEO tools within CUBASE but found them too cumbersome.
So, do you intend to make similar videos for fun, or are you going to create some CUBASE tutorials in the future?
Best,
Paul