I\'m surprised you are having syncing problems. I have had tkcvideo for a few years and watch a lot of videos on my Z. Mind you, I do not try to fast forward or rewind, which always interrupts the sync, but if I play a video start to end it is usually perfect.
My best advice is to try something like Dr. Divx to creat the video and use the Handheld settings at 320x240 or 640x480.
I used to create videos using VirtualDub, but Dr. Divx seems to be easier to use.