Follow the link to a review I did on the TrackIR3 Pro about a month ago. The first part is a little background on the TrackIR system and how it works. The second part is a comparison between the TrackIR2 and TrackIR3.
I hope you find it interesting.
I just watched some of the videos, that's a fascinating tool, thanks for posting it.
More Info on TrackIR: