QuickTime Player in OS X Lion has the capability to merge multiple video clips into one movie. Simply drag the clips you want to add into a movie window. QuickTime Player will automatically scales or crops the clips so they match the dimensions of the movie. You can even trim the head or tail of any clips before saving the combined clips as new movie. If your video editing is just trimming and combining clips, instead of the more elaborate iMovie, you can just use QuickTime Player to achieve the same result.