Its to due to the lossy of the video..
The D90 does not allow me to change the video compression codec for in-camera recording. This poses another question: should I record to an external hdmi recorder in stead of in the camera?
I think however the fact that the D90 can not record full HD has also got something to do with quality. If I want to cram all the data of a fisheye image into a half HD (1280x720 pixels) movie and combine that with 12MP still images to make a panorama, I guess I can't ask for sharp results.
However, the examples here on the Kolor website look good. So that is why I was wondering how they were recorded.