I hope uploading new firmware would improve the quality of your recording:
Connect the camera with the computer.
Turn the camera on.
Click onto the link and follow the instructions.
http://wwwuk.kodak.com/global/mul/service/downloads/DownloadLookup.jhtml?pq-path=15372/15504&product=EKN036561
If it can be of any help I did manage to find information on how can I eliminate noise during video recording on the Zi8:
Turn off Continuous AF (auto focus) to prevent recording camera noise during video capture. When you turn off Continuous AF, you may notice a narrower area of focus or depth of field, especially if you zoomed to a telephoto position before recording.
- Turn the Mode dial to Video, then press the Menu button.
- Highlight the Continuous AF menu, then press the OK button.
- Highlight Off or Single AF (certain models), then press the OK button. (On is the default.)
- Press the Menu button to turn off the menu screen.
This setting remains until you change it, change the Mode dial, or turn off the camera.
Good luck I hope one or both solutions will help the problem