: Right-click the file and select Open with > Windows Media Player or Movies & TV .
Most modern devices can open MP4 files natively. To view 3729.mp4 : 3729mp4
: Use QuickTime Player , which is built-in and based on the same standard as MP4. : Right-click the file and select Open with
If 3729.mp4 won't open or has no thumbnail, it may be corrupted. Common causes include: Why is my mp4 video file unsupported? - Facebook 3729mp4
