There are two different video file formats known as Flash Video: FLV and F4V. The audio and video data within FLV files are encoded in the same manner as they are within SWF files. The F4V file format is based on the ISO base media file formatand is starting with Flash Player 9 update 3.
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.