M100’s codec is stil not a Universal Binary, it needs to open under rosetta – what application are you trying to use the Media 100 files with in?
If you are simply trying to open them in Quick time – go to the application folder for QT – get info on the QT application icon (cmnd+I) , somewhere with in that dialog, there’s a check box ‘open in rosetta’ when you click this, QT will run in rosetta and allow you to access the m100 codec.
You would have to do this for any application you wish to use with the m100 codec (I think) – or use QT pro to then export to an intermediary codec like, say, animation codec.
hth
~A.D.