Thanks for letting us know your results.
Motion blur relates to the blur from motion in the video and to no other sources of blur. These are often large blurs, directional smears of the image, that can be inches long. Usually motion blur is a problem only with the higher speed athletic motions in a video. The rest of the picture should be clear but the golf club, throwing arm, ball, etc., has considerable blur. Is that what you have?
Tripod. Motion blur can also be produced if the camera is not held steady and moves while the shutter is open, that is, with a slow shutter and a hand held camera. Use a tripod to eliminate the camera's contribution to motion blur. Motion blur from an unsteady camera will be everywhere. It will always show the direction that the camera was moving when the shutter was open - all blurs sideways or up and down, etc.
Kinovea can't produce motion blur. To check this point and any other viewer blur differences look at your video in another viewer with excellent stop action such as Quicktime. That should show the motion blur in the video and any other blur differences.
Also, research the shutter specifications of your cameras in the users's manuals or on the internet.
I have no understanding of video compression issues that might might relate to your cameras or even if that could be an issue. My Casio FH100 camera can be set to produce videos for Youtube. I assume that those files would be compressed and probably not useable for some stop action purposes but I don't know.
Have your friend upload a video to Vimeo or other video website that does not compress_CORRECTION SEE BELOW_the video (not Youtube) and view it yourself. If possible do some experiments with your friend under identical conditions.
Details on compression & non-compression as used by Vimeo are described in these FAQ-
http://vimeo.com/help/faq#compression