Bueno, hace mil años que no uso MAC así que tal vez otros te sepan decir con más detalle lo que quieres. De momento te paso todo esto en inglés. Sí te puedo contar que el Avidemux es bastante sencillo y que el iMovie es gratis, o lo era, y cumplía su función. En fin, ¡suerte!
MAC OS X:
iMovie
iMovie that comes with every new Mac (OS X), now called iMoveHD and it's a part of iLife package. Apple iMovie '05 is an excellent (and free) video editor for the Mac platform, with advanced video editing features and a lot of addon and plug-in support. You can find more information about iMovie at Apple's iLife '05 site. Note that this software is free only if you buy a new Mac. You can purchase it, however, if you just want the software.
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Register or Loginhttp://www.apple.com/ilife/imovie/
Blender
model • shade • animate • render • composite • interactive 3d
Blender is the free open source 3D content creation suite, available for all major operating systems.
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Register or Loginhttp://www.blender.org/
Avidemux
Avidemux is a free video editor designed for simple cutting, filtering and encoding tasks. It supports many file types, including AVI, DVD compatible MPEG files, MP4 and ASF, using a variety of codecs. Tasks can be automated using projects, job queue and powerful scripting capabilities.
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Register or Loginhttp://fixounet.free.fr/avidemux/
Jashaka
The worlds first open source, hardware accelerate editing and effects system! Well worth to check it out.
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Register or Loginhttp://www.jahshaka.org/
HyperEngine-AV
Multimedia authoring software for capturing, editing, organizing, processing, and exporting video, audio, and text to create DVD quality movies and slide shows.
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Register or Loginhttp://sourceforge.net/project/showfiles.php?group_id=131273
Atomic Learning's FREE Video StoryBoard Pro
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Register or Loginhttp://movies.atomiclearning.com/k12/storyboardpro
ZS4 Video Editor
ZS4 Video Editor is video editing and compositing software which aims to provide media experts with a facility to combine a variety of media types (currently photos, videos and audio files) into one (or more) output file(s).
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Register or Loginhttp://www.zs4.net/free-software-downloads
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