I've been searching around for a solution to play m2ts for Mac OSX and found this tutorial:

http://www.0ctane.net/files/readme_osx.txt


original discussion can be found here (for Linux as well):

http://www.avsforum.com/avs-vb/archive/index.php/t-789775.html


For Mac OSX, it works. I finally can play the video using mplayer. but I thought the step converting to YUV is bad. it takes long and a lots of disk space... oh well..

just sharing...