A client gave me a file in Windows Media Video format. I need to edit it in Final Cut Pro X. The problem is that Final Cut Pro X can't read it. Neither can Apple Compressor. It has a Quicktime logo, suggesting that Quicktime can open it, but Quicktime cannot.
I can recommend Adapter.
It is a Wrapper for the ffmpeg package and does its job pretty well. Because of its easy UI. You could also use ffmpeg directly via macports, but I think that Adapter is far easier to control.