Download VLC Media Player . It is free, open-source, and plays almost any file format without needing extra codecs.
The .M4V file format is a video container developed by Apple. It is very similar to .MP4 , but it can sometimes include DRM (Digital Rights Management) protection if purchased from the iTunes Store. However, when coming from your camera roll, it is simply a high-quality video file compressed using the H.264 codec. Common Issues and Solutions IMG_3147.M4V
Surprisingly, you can often just change the extension from .m4v to .mp4 manually, and most players will still read it. Download VLC Media Player