762777.mp4

: Use QuickTime Player or Adobe Creative Cloud tools if editing is required.

If you downloaded this file from an untrusted source or received it via an unexpected email: 762777.mp4

: Run it through an antivirus program or upload it to VirusTotal before opening. : Use QuickTime Player or Adobe Creative Cloud

: If the default player fails, download the VLC Media Player. It supports almost all video codecs and is highly recommended for unknown or stubborn files. Identifying the Content 762777.mp4

Could you share or its file size ? That would help narrow down exactly what "762777" refers to. How to play MP4 files in Windows - Microsoft Support