This is taking the long way home but to record Orbiter movies for the kids school projects, I jacked my video card to a VCR (mastering quality tape...the low grade stuff is just garbage). Once the raw footage is recorded, jacked the VCR back into the PC and edit to your heart's content with Vegas (or editing software of your choice).
Framerate remains constant (whatever Orbiter runs at on the machine in question anyway) since you're not taxing your system resources to record the video as it's playing back (which is the problem with Fraps & other capture software). There's no figuring out the correct time accel/deceleration to get a usable video capture.
Obviously, you need to have a video card with "line in/out" jacks so it won't be the answer for everyone, but it's another option worth considering.