QuickTime is Apple's proprietary media player. The application is distributed in free basic versions for Mac and Windows systems. Apple developed MOV as a digital video format that works natively with QuickTime. Although an MOV file may compatible with QuickTime, it may fail to load in the media player for one of various reasons.
Digital videos like MOV files are all products of compression. During compression, multiple streams of media (i.e. audio and video tracks) are written with a special algorithm called a codec. A codec is a script that translates digital information into a readable format. Once the media has been processed through their respective codecs, they are subsequently merged into a single file through a multimedia container. If your MOV file fails to load in QuickTime, then it is possible that your system is not equipped to read the digital video's codecs. Once an MOV file is opened in QuickTime, you can identify its codecs by going to the "Window" tab on the program menu and selecting "Show Movie Inspector." The media's codecs will be listed in the "Format" field. Some utilities that activate codec support in QuickTime include the QuickTime MPEG-2 Playback Component, DivX, Xvid and Autodesk.
If QuickTime fails to play your MOV file, then it is possible that your installation of the application is obsolete and no longer supported. The media player may not be able to read the digital video because the technology that was used to encode it was recently developed. But when it comes to updating your version of QuickTime, it is not necessary to un-install and re-install the application. All you have to do is go to the "Help" tab on the program window and select "Update Existing Software…" Follow the on-screen directions to obtain the latest version of the media player.
When digital videos are distributed, it is possible for their filename to change. These changes can also carry over to the media's file extension. While a file extension reveals what type of data is contained in a file, it also indicates which type of software should open the file. But since file extensions can be easily edited, they may not always be accurately assigned to files. As a result, your MOV file may not load in QuickTime because it has been misidentified as a digital video that is compatible with the application. But free tools like MediaInfo and FileAlyzer can analyze a problematic file's properties and confirm if it is using the right file extension.
If your MOV file fails to load in other media players besides QuickTime (e.g. iTunes, VLC, GOM Player, Zoom Player), then the asset is probably corrupt. Since the digital video was not properly encoded in the first place, it cannot be read by QuickTime ( or any other supported application) even it is a compatible format.