The MKV format, which is a container format developed by Matroska, can hold a variety of video and audio codecs. Its compatibility with Mac is not very satisfying, so if you convert those MKV/HD MKV movies, videos, or TV shows on your Mac to MOV files, you can play them with QuickTime (QT), edit them in iMovie or Final Cut Pro (FCP), and conveniently stream these converted MKV/HD MKV movies to Apple TV, iPod, or iPhone.