: Before playing an unknown file, upload the hash or the file itself to a service like VirusTotal to ensure it does not contain malware.
: Some applications rename MP4 files to long alphanumeric strings to prevent users from easily identifying or playing them outside the intended app. How to Safely Identify the Content
The alphanumeric string likely refers to a specific file hash (such as an MD5 or SHA-1 identifier) or a unique system-generated filename for an MP4 video file.
: Use a tool like ExifTool to see when and where the video was created without playing it.