M4V is a video container that stores audio and video data used for iTunes files. Files of this type may be protected from illegal viewing and copying with Apple FairPlay DRM. In this case audio or video files should be bought in iTunes store. Not protected files can be viewed almost in any modern player because the format is based on MPEG-4 structure.

MXF is a media container developed by SMPTE association for professional use. MXF implements subset of Advanced Authoring Format (AAF) data model and nowadays become a standard in professional non-linear video editing. MXF files can be compressed with almost any codec and easily converted to any popular video format. Worth noting that Sony's, Panasonic's and Canon's implementation of this format carries a lot of incompatibilities, that was a big flaw of this container. These issues were addressed in the 2009 version of the standard.