Just make sure you don't make it bigger than the size of your recorded clips
example: 640x480 clip saved at 800x600 will look TERRIBLE, where as a 800x600 clip saved at 640x480 would look fine.
I'd go with recording your stunts at 800x600 and rendering your video as 640x480 with a variable bit rate of 1.5M - 2M, thats what I did for animosity and it turned out good quality and acceptable filesize IMO