The file appears to be a generic video file, likely a temporary download name or a specific asset from a game or educational software. Without more context on where you found it, How to Open the File
: Certain university courses use specific numbered MP4s for coding assignments or documentation guidelines. Safety Warning 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 The file appears to be a generic video
: Run it through an antivirus program or upload it to VirusTotal before opening. check the following:
If you are unsure what the video contains, check the following: