Is a the most popular media container format on phones without the support of 3G, which is currently somewhat outdated. Its main advantage is a compactness. Video data here gets stored in h.263 or MPEG-4 formats. AAAC-LC or AMR-NB are available for audio.
The *.m2v 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. M2Vs are created by demultiplexing (demuxing) an existing MPEG-2, or by converting another video format to MPEG-2. The file extension m2v is mostly found with SFV Host Files.