: You can use the CloudConvert MP4 Tool for a quick online fix, or Handbrake for a more professional, desktop-based conversion.
If your standard player (like Windows Media Player or QuickTime) won't open it, the file might use a specific "codec" (the way the video is compressed). 3716mp4
: Right-click the file, select Get Info , and check the "Name & Extension" section. 2. Use a Universal Media Player : You can use the CloudConvert MP4 Tool