One of the first things I noticed about Vegas is that you can yank the original sound (engines, cockpit, environment, ect.) out of the video track if needed for the shot

Another nice thing is being able to crop the "replay" and "traffic replay" and other like messages out of the video by cropping off the bottom portion where those messages appear. I also like being able to have multiple audio tracks

I have also found another fun resource that I'm going to try working into future videos - LiveATC.net. They offer streaming (and downloadable in mp.3 if you have the right Firefox add-ons) real world ATC from a sizable number of airports around the globe. I've tried it in regular flights and it adds a significant "real world" feel to the flight to hear live voices instead of FS9's semi robotic ones.
The addy for LiveATC.net is:
http://www.liveatc.net