One of the issues I had with the screencasts I was doing for Cincom was that the Windows ones often had frame skipping problems. It turns out that tyhis was due to a simple mistake I made in configuring the VM.
When you have a VM stopped, you can edit the settings. One of those deals with optimization - should your system favor native (OS X) apps, or the VM? The default is to favor the VM. This is great if you're playing a game, or running a fairly intense Windows app, but it's not so good if you are using a Mac App to capture the Windows screen.
The solution? Simple - just flip the optimization over to favor OS X apps. That solved the frame drops for me nicely.