MKV Player is a very easy to use video player. It can be associated with your MKV files and all other video files so you just need to double click the file to play it. All basic functions like play, pause, seek, fullscreen are available.
You can also make your own playlists, save them, edit them. If you have a large number of video files, you can use built in search to find your favorite from the list. You can change language and subtitles if available. You can also play very high bitrate files even on old computers. In all this is a great package for those who want to keep things simple.