You could use VLC player to capture video from your desktop. I'm not sure if you'll get enough fps but i'm sure you'll get better resolution. There's a lot of tutorials available for capturing video with VLC, it's pretty straightforward thing to do.
It is high quality and internal. What is more, it gives you a tool for changing a camera view during sim.
I often use Screencast-O-Matic for full screen capture. There is a free version and a cheap pro version. I did end up getting the pro version, but if your just doing short videos the free version is pretty good. There is a watermark on the free version though. I think the paid version was $10 a year or something like that. It records high quality video and can capture the computer audio, mic audio, and webcam too if you so desire.