In this video tutorial, viewers learn how to use chroma key in iMovie '09. This video teaches users how to use chroma key to replace the background of videos. Begin by opening the program. Now drag or image or video background into the time line. Now click on iMovie and select Preferences. In the General tab, check the Show Advanced Tools option. Then simply drag the video that you want over the background image/video in the time line. This video will benefit those viewers who enjoy creating video with iMovie and would like to earn how to use chroma key to replace the background of their videos.