AMV (acronym for Anime Music Video) represents a video format which contains one or multiple anime clips with audio background. AMV files are usually created by anime fans and are not official.
They are typically created to synchronize anime series with audio files chosen by the users which subsequently release the AMV file over the web.
This format is currently supported by several multimedia processors that can play and convert AMV to other formats.
Also, AMV players can also be used to create custom playlists that contain AMV files and tracks of other formats.