Open Photo Booth by clicking the icon in the "Application" system folder of your Mac computer.
Record your video by pressing the camera button in Photo Booth. When you are finished recording, press the camera button again to stop recording.
Select the GIF video file from your Photo Booth time line. Drag the GIF file to your desktop. This will automatically save your file as a MOV file instead of a GIF file.
Open QuickTime Converter from your list of applications. Drag the MOV file into QuickTime, and from the "File" menu select "Export." Select the option for AVI, and click "OK." This will export your file as an AVI file. If you don't wish to use QuickTime Converter, you can use iSkySoft Video Converter or MOV to AVI Converter for Mac.