: Many dashcams, bodycams, or security systems use prefixes (like "BOY") followed by a sequence number.

: Ensure it is actually an .mp4 and not a double-extension file like BOYST0250.mp4.exe , which could be a virus. To give you more specific advice, could you tell me: Where did you find this file?

: It may be a clip from a specific stock footage library or a private backup.

: Run it through a scanner like VirusTotal before opening.

: Use VLC Media Player , which can play almost any .mp4 regardless of the internal codec.

: Often hidden in the metadata, showing exactly when the footage was captured. 4. Safety Warning If you downloaded this file from an untrusted source: