How to Resize QuickTime MOV on a Mac
Movies can take up an enormous amount of space on your hard drive; QuickTime movies' large size can make them difficult to upload to the Internet or to share. By using the iMovie program that comes with Macs, you can resize the movie to your own specifications. Making the movie file smaller will make it easier to upload. You can also make the movie bigger, though it will cause a loss in image quality---especially if you increase the size a great deal.
Open iMovie on your Mac, and start a new movie by clicking "File" and then "New Project."
Import your QuickTime movie by clicking "File," then "Import" and "Movies." Click the file from the menu that appears to select it.
Drag the movie from the media library in the lower right corner of the iMovie window to the project window in the upper left corner.
Click "Share" at the top of the screen and then "Export using QuickTime."
Click "Options" at the lower right corner of the pop-up window.
Click the "Video" check box if it is not checked, then click "Size."
Click the size you want from the drop-down menu to select it. Larger-size movies will be significantly larger files.
Click "OK" on the "Size" window, then "OK" on the "Settings" window name your file and click "Save" to complete the export and resizing.