In most cases, that's because your video file is in the wrong format for Mac (MacBook/iMac) default QuickTime player. When it comes to play video on iMac or MacBook, QuickTime won't open or QT quits unexpectedly issue occurs.
Yet, you can't control your video source codec or format. Your video footages come from everywhere, be it YouTube, Ins, GoPro, DJI, camcorder, screen recorder, mobile device or Windows.
