I use something called 'kdenlive'.. a tiny bit like iMovie; very powerful, but nowhere near as polished.
There's a mac port here: www.macports.org
if want to play with it (but I'd recommend sticking with iMovie if you have access to it).
For the Google earth stuff, I use a desktop recorder program.
I create an invisible 'pin' at the spot / height that I want to end up at, zoom out, then activate a desktop recorder. The one I use is only available on linux, but here's a free one that should be pretty similar for windows:http://sourceforge.net/projects/camstudio/
Dunno about Mac unfortunately - have a look at screenium, screenrecord, or similar; those names popped up a bit when I did a brief google check.
Then it's just a matter of activating the recorder, then double-clicking on your push-pin link.
Once that's done, use your video editing software to 'crop' the resulting video to cut out the google earth side/top/bottom bits.