Read at answers from apple discussions:
A MOV file is basically and MOV file container containing any form of compatible data. Thus, it is often helpful include information regarding what form of data is actually contained within the file.
Since the original file was recorded on an iPhone, the MOV file should contain H.264 video with AAC audio and should be compatible with both the QT X v10.3 and QT 7 players under Mavericks. However, since the file was obviously edited (at least the filename was changed), can you confirm the type of data actually contained in the?
In some cases, an iPhone (H.264/AAC) video may not open correctly in QT following security and/or system updates. In some cases, simply rebooting the system may "fix" the problem.
Another possible test you can run is to try and play the file in a third-party media player. If the file plays correctly, then the file is okay and the problem is most likely associated with the codec configuration, the player app, the PLIS file, etc. and you will have to run further tests.
In still other cases, a file may become corrupted during editing or transmission.