The only way I figured out how to do it:
Write video: make sure you save it as an .AVI
When done open it in Windows movie maker.
You can edit it pretty easy even add text, cut it in pieces etc.
When you save in movie maker it takes forever, a 15 minute film will take hours to save.
Don't know why. Then upload in windows movie maker file.
So if you overlay only say 4 laps at the time you save a lot of time by merging them seperately instead of merging a session and then cut it in pieces, but if you do, you can add text. Like so:
http://www.youtube.com/watch?v=zPf0BJ3D9tQ
You can see why I wanted a normal HD camera instead of the crappy Chasecam they sold me first ;-)
My house is without internet, so I will likely be offline till tomorrow.