Working with video files is often a complex and confusing task. Something as simple as shrinking a movie file can become tedious if you haven't a clue what you're doing. Do not fret, though, as there are several resources to help you accomplish your objective. Though you shouldn't be afraid to experiment with settings, re-encoding video can often take a long time. While working with Apple's .MOV file extension, there are several tools available to help shrink your movie.
Download the latest version of QuickTime. (See "Resources" section for link) You can choose to upgrade to QuickTime Pro for more options, though it is not necessary for the purposes of this article. QuickTime will allow you to change your .MOV file in many different ways, including shrinking the file size. Open QuickTime and the movie file you intend to shrink.
If exporting the video in an e-mail, click the File menu and select Share. You will then be prompted to choose a size for the new file (small, medium or large). Beneath that is a display showing how large of a file the resulting video will be. When sending movies over e-mail, it's generally best to keep file sizes under 25 MB.
For greater control over the size of your movie, click the File menu and select Export. Specify where to save your new movie. Under the Export heading, make sure you select "Movie to QuickTime Movie." This will ensure your new file is a .MOV. Under the Use heading, select which setting best describes how you plan on delivering your movie (e.g. dial-up, broadband, streaming, etc.). You may also leave the setting at "Default Settings."
Click the Options button. From there select Settings under the heading "Video." Adjust the Quality bar to a lower value. Use the video frame to the right to see how the quality slider affects the image resolution of your movie. When you find an acceptable setting, click OK.
Select Size from the Movie Settings window. Specify a suitable size for your new movie file. A smaller resolution will yield a smaller file size. Several standard resolutions are available in the drop-down menu, or you can enter a custom resolution, though this is not recommended if you are not sure what you are doing. Click OK when finished adjusting the size of your video.
Finish the process by clicking the Save button. The video will then begin encoding, which may take several minutes depending on the options you chose. When the encoding process is complete, check your new movie file to make sure it looks acceptable and is within range of the size you wanted.
Alternately, you can try using a program designed specifically for shrinking .MOV files such as MPEG Streamclip (See "Resources" section for link.)
Be careful not to delete your original (larger) file, as once you down-convert the resolution, it is impossible to regain the movie's original clarity.