“M4V is Apple's version, which adds optional DRM-encryption. So if the video is DRM-protected... it should stay as m4v.” Reddit · r/PleX · 8 years ago
If you're having trouble playing this specific file, you can try opening it with the VLC media player or using a tool like HandBrake to convert it to a more universal format. What Are M4V Files? | M4V Format Explained - Adobe RockBlackDoll.m4v
If the file was purchased or rented from the iTunes Store, it likely has DRM, meaning it can only be played on authorized devices. What Are M4V Files
Users often find the M4V format confusing due to its similarity to MP4 but restrictive nature on non-Apple devices. If the file is unprotected, it can often be renamed to
If the file is unprotected, it can often be renamed to .mp4 and played on most standard media players without any quality loss.