The VLC media player is designed to play back almost any type of media file on nearly any system. However, this media player isn't without errors, and QuickTime's MOV file type can sometimes confound the player. VLC comes with most necessary codecs preinstalled, including MOV-relevant files, so there are only a handful of reasons VLC won't open your MOV files.
Streaming and QuickTime
According to the VLC documentation, the solution to playback errors in MOV files is to open the file using the QuickTime player for a couple of seconds to let the QuickTime player optimize playback. After a few minutes, pause the video in QuickTime. Then open up the stream info and copy the URL. Use the URL to open the file in VLC via the "Open Network Stream" option; you can reach it by pressing "Ctrl" and "N" on your keyboard.
VLC should come with everything you need to play MOV files. However, if you've tested your MOV files in another player and you're unable to get your video to play at all, you may be missing the relevant codecs. You can get these by downloading QuickTime for your platform, although a version is not available for Linux. The QuickTime Alternative codec pack is a third-party package available for Windows users; this way, you can avoid installing it if you consider it unnecessary. If you use Linux, you can employ FFmpeg, which supports MOV files.
Video Errors and DRM
It's possible that the video is damaged or corrupted; this can happen when a file is copied. If you downloaded the file, it may not be finished downloading or may have encountered errors while downloading. The best way to test this is to use another player or to copy the video to another computer for testing. If you can have access, download or create a new copy of the video. Note that VLC cannot play content protected by digital rights management.
The most obvious alternative for MOV files is QuickTime, but this is only for users with Windows or Mac computers; if you have Windows or OS X, you can also use iTunes to play your MOV files. Windows Media Player can play MOV files with the appropriate codecs. Another option for Windows is GOM Player, a free and simple media player that comes with the necessary codecs.