At least I found a way to play back the movie files on my Mac. The free VLC program handles AVCHD, although it does not recognize the .MTS extension: [http://answers.yahoo.com/question/index?qid=20090519052402AABrVSL]
+To associate the AVCHD Lite (MTS extension) in the future so that VLC will always play (...) Select the file, Get Info, choose Other to select which application to open with, choose application (navigate to where VLC located and will be unavailable - to make it available, drop-down where it reads Recommended Applications and choose All Applications). Select VLC program (with the cone icon), choose, and then make default and confirm (changing to the terminal exec icon). Double-click on the file and enjoy watching AVCHD Lite!+
I put an alias to the PRIVATE/AVCHD/BDMV/STREAM folder in the root of my card for easier access to the MTS files ...