I wrote this up for Dan, so I thought I'd share. Most Sony digital still cameras can also record movies, which is great. The only problem with the videos is that they are multiplexed ("muxed") -- the audio and video are intertwined in a way that iMovie doesn't understand, so you get a silent movie if you try and edit it. After the jump, a workflow to get editable footage from a Sony digital camera using only free tools:
This workflow uses two tools -- the video convertor ffmpegx and the audio editor Audacity. (ffmpegx is actually $15 shareware, but it has full functionality forever, so you can be a jerk and use it for free.)
Launch ffmpegx, go to the Tools tab and then Demux. Click the browse button and then find the movie file, then click the Demux button. After it's done processing, you've got two new files - a .m1v file, which is the video, and a .mp2 file, which is the audio.
Next, launch Audacity and open the .mp2 file then choose File >> Export WAV.
Open iMovie, make a new project, and choose File >> Import and choose the .MPG or .m1v file (it doesn't really matter). Put the clip onto the timeline, change to Timeline Viewer (by clicking on the little clock in the lower left or View >> Switch to Timeline Viewer). Make sure the playhead is right at the start of the clip (if you haven't touched it it will be) and choose File >> Import and pick the .wav file.
Now, you can edit your movie. Annoyingly, to make cuts you need to do ⌘-T (Edit >> Split Clip at Playhead) on both the audio and video clips. But it's free!