Interesting experiment 
(Disclaimer, the following is just guess, as I don't have an iPod and I haven't checked how its web server or camera works…)
First of all, I think you need to look for the actual stream (video or constantly overwriting image) address, not the web server's.
When your browser connects to the web server it is probably processing a web page embedding the stream, but if you want it to work in Kinovea you want the raw stream address directly.
(The URL should end with a script's name + parameters, or directly the stream file. With just the server's address, it means we are defaulting to something like index.html which would then contain the actual call to the script or file. Kinovea cannot parse the HTML to extract the camera URL).
Secondly, the stream must be MJPEG or JPEG, as they are the only IP camera streams supported in Kinovea. If it's H.264 or something else, it will not work. (If WebcamXP support the format you might use it as a "man in the middle" : you connect it to the stream, and then connect Kinovea to it).
Let us know about what you find !
