.mp4 (A standard digital multimedia container format most commonly used to store video and audio). Common Origins
This naming convention is frequently used by platforms that need to give files unique names instantly without user input: 1565839234123 mp4
Since the file has an .mp4 extension, you can open it using any standard media player: Windows Media Player or Movies & TV . macOS: QuickTime Player . 1565839234123 mp4