iMovie 2013 provides a great way to create stunning videos, short movies, music videos and other creative projects. Once you finish your project, iMovie gives you several ways to export your movie to one of the built-in movie players on Mac OS X Mavericks. You can loop a movie directly within the iMovie application. However, if you want to export the movie, you must use QuickTime to loop the movie continuously. Both the free version of QuickTime that comes pre-installed on your Mac and QuickTime Pro provide the ability to loop videos.
Launch iMovie and open the video you want to loop.
Click the "View" menu and select "Loop Playback." Once you start playing the video, it continues to loop until you stop the player.
Select the "Share" button when you want to export the movie to another application.
Choose the "File" option and click the "Next" button.
Click "Save" to convert and save the video.
Right-click the file, select "Open With" and choose the "QuickTime" option.
Click the "View" menu and select "Loop Playback" from the drop-down menu to loop the video continuously. With QuickTime Pro, you can loop a movie so that it runs forward and then in reverse by clicking the "View" menu and selecting "Loop Back and Forth."