How do I trim a video in Quicktime?
You can use QuickTime Player to trim your video files. To Trim a Video, use the following steps:
In QuickTime Player , select Edit > Trim, so that the trimming bar appears.
Use the Trimming Bar to select the portion of the movie that you want to keep. Dragging the highlighted areas to make your selection.
Click the Trim button and the movie will be shortened to the portion you selected.
Don't forget to Export your movie to your desired location. To do this go to File > Export and select either 1080p (HD), 720p or 480p (SD).