iMovie is a desktop video processing package that comes
freely bundled with MacOS. 

This is the "export" instructions for iMovie users:

1. Open your iMovie Project.

2. Under the FILE menu select "Share"

3. A window will open.  Along the top there are several export icons
   (email, Homepage, etc). Select "QuickTime"

4. The next window will ask, "Compress move for".  Under the option,
   choose "Expert Settings". Then click on the Share button.

5. A new window will open titled "Save exported file as"  Near the
   bottom of the window set the "Export:" to "Movie to QuickTime Movie".

6. Next to the Export selection is a button labeled "Options".  Click
   on it to open the "Movie Settings" panel that displays video and
   audio options.

7. Under Video, choose "Settings" .  This will open the Compression
   Settings window. Under the Compression Type options, choose 
   "Sorenson 3".  Set the Compression Quality setting between the 
   Medium and High setting.  Click "OK".

8. Under Video, choose "Size".  Click the "Custom Size" button that
   will then allow you to set the width to 720 and the height to 480.
   Click "OK".

9. Under Audio, choose "Settings".  Then under Format, choose
   "Qualcomm PureVoice"  Click OK. In the "Movie Settings" panel, 
   click "OK".

10. Be sure to name your movie and select the destination for 
    your new file. Click "Save".