: Right-click the file and select Open with > Windows Media Player or Movies & TV .

: Use VLC Media Player —a free, open-source tool that can play almost any MP4 regardless of the internal codec used. 2. Common Causes of Issues

Most modern devices can open MP4 files natively. To view 3729.mp4 :

: Use QuickTime Player , which is built-in and based on the same standard as MP4.