: Right-click the file and select Properties (Windows) or Get Info (Mac). Look at the "Origin" or "Camera" section to see what device created it.
: Likely a low-resolution proxy or a very short "event" clip from a dashcam. g4_0139.mp4
To help you review the content, here are common ways to identify what that specific file might be: Common Sources for "G4" Filenames : Right-click the file and select Properties (Windows)