If iMovie is not suitable for you, i have another 4 free video editing software for your Mac here:
- First, Avidemux
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.
- Second, Blender
Blender is a free 3D graphics application and considered as one of the best free video editor for Mac. It can be used for modeling, rigging, texturing, UV unwrapping, skinning, animating, rendering, water and smoke simulations, particle and other simulations, non-linear editing, compositing, and creating interactive 3D applications, including animated film, video games, or other visual effects.
Blender has lots of advanced features like powerful character animation tools, modifier-based modeling tools, a node-based material and compositing system, Python for embedded scripting and so on.
Like Avidemux, Blender is available for Microsoft Windows, Mac OS X, GNU/Linux, FreeBSD and OpenBSD.
- Third, ZS4 Video Editor
ZS4 Video Editor is a free video editor for Mac which provides media experts with a facility to combine a variety of media types into one (or more) output file(s). Besides Mac, it is also available for Windows and Linux.
ZS4 Video Editor comes with over 150 built-in video effects which can help you bring your videos to the next level instantly.
- Fourth, HyperEngine-AV
HyperEngin-AV is a free video editing software for Mac used to capture, edit, organize process, and export video, audio, and text to create DVD quality movies and slide shows. It comes with twelve studio-quality effects from Arboretum's Hyperprism suite of audio processors. Besides, it offers text features to display credits, section titles, or karaoke lyrics with fully editable font, size, type, color, style, alignment, and scroll direction. Definitely, HyperEngin-AV is really a good free video editor for Mac users.
You can check my detail articles about top 5 free video editing software for mac users here: http://www.wondershare.com/video-editor/free-video-editing-software-mac.html (Full disclosure, I work for the company that made the top 5 list.)