Let's say you've shot a quick video on your mobile phone or video camera. Then you've loaded it onto your Mac computer. But before you use the video, you want to trim some of the unwanted footage. This video shows you how to do just that using imovie. Of course you could use quicktime to do exactly the same thing, but doing it in imovie also gives you the option of doing a little bit of additional editing if you want, such as adding titles, combining clips adding transitions, etc.