How to make a Google Earth movie with free software
Starting with the free version of Google Earth, I installed FRAPS, a program that saves the video from programs that use DirectX (mostly games) directly to the hard drive in an uncommpressed avi format. Works real nice, makes good quality movies, but with a very large file size. FRAPS uses a codec that can not be read by anything else. So, using VirtualDub (installed on the same PC as FRAPS), I converted the avi to a much smaller Divx Avi. From there I could edit/play the video on anything, like my Mac!
The tool chain used here is pretty obscure for a normal person, but is probably usable by an interesting fraction of the early adopters that have jumped on the new interfaces for Google Maps / Google Earth.
The user-friendly way to make a Google Earth movie is to pay for the upgraded version, which adds several features, including movie output ($400).