Toby,
I have a Mac and have fussed around with Quicktime for a couple of days trying to get your videos to play. The solution I found that DOES work is "MPlayer OSX Extended" for the Mac. 22MB download, 1 minute install, and it plays your videos just great.
Here is the link to download:
http://www.macupdate.com/app/mac/282...-osx-extended/