The file appears to be a video file that has been accidentally double-extended (containing ".mp4" twice). This often happens when a user manually adds an extension to a file that already has one hidden by system settings. Understanding the Double Extension
If you are trying to "write" or generate this file programmatically:
: Despite the odd name, the file is still a standard digital multimedia container used for storing video, audio, and subtitles. How to Fix or Use the File