M2V is an
MPEG-2
Packetized Elementary Stream. It contains only video
related data.
MPEG-2 video stream files are normally destined to be multiplexed (muxed), which is the process of adding audio data and perhaps other streams such as subtitles, before use. MPEG-2 stream files are created by demultiplexing (demuxing) an existing MPEG-2, or by converting another video format to MPEG-2.