iMovie comes with every new Mac (OS X) and you don’t need to pay extra money for it. The latest iMovie 11 is a great and free video editor for the Mac with many great features such as movie trailer, one step effect, audio editing, etc. And in just a few steps, you can share your movies to YouTube or export videos for your iPhone, iPad, etc. However, iMovie is only free if you buy a new Mac. And when getting started with iMovie, you will find it hard to master this software. All in all, iMovie is one of the best free video editing software for Mac users and receives good reputation. You can learn some iMovie video editing tips and trick at how to use iMovie.
Note: iMovie supported video formats are very limited to MP4, MOV and M4V. If you want to edit flash videos in other formats in iMovie, you can use a swf converter mac to convert the videos first. Otherwise, you should turn to other flash editing software mac which supports many video formats, like Wondershare Vivideo Editing Software for Mac.
Avidemux is another great free video editor designed for simple cutting, filtering and encoding tasks. It is available for Mac OS X, Microsoft Windows, Linux and BSD under the GNU GPL license and supports a variety of video, image and audio formats, including AVI, DVD compatible MPEG files, MP4, MOV, ASF, JPG, AAC, AC3, etc. High compatibility with many video formats is the highlight of this free video editing software for Mac.
original from: flash blog