Tool:Xilisoft Video Converter for Mac

Step 1: Load M4V files.
Run Xilisoft Video Converter for Mac. Click 'Add File(s)' button to load your M4V files.

Step 2: Set output format and output folder.
Choose M4V files you want to convert, and click 'Profile' drop-down button to choose output file format. You can choose 'AVI - Audio-Video Interleaved (*.avi)', 'DivX Movie (*.avi)' or 'XviD Movie (*.avi)'.

Click 'Browse' button to choose destination folder for saving your converted AVI video files.

Step 3: Convert.
After choosing the format, you only need to click 'Convert' button on the toolbar to complete the M4V to AVI conversion task.

Ok, done.