I just use Camtasia 5, and depending on where I want to display it, I then choose the appropriate format for production. I've really not done anything special, other than a lot of trial and error on production formatting for size.
The videos on this site for Revver are all .wmv files. I pretty much record everything at 1024x768, and whenever I scale the size down for production, I do it proportionately - i.e. it's a percentage of the original height and width, so there's no distortion (never 800 x 600)