Video is the heaviest thing most of us ever attach: screen recordings, camera clips, whole talks. It was born in wherever your camera, screen recorder or download came from, and its real weak spot is nothing inherently; every container brings its own quirks.
MKV is the format that hoards: video, a dozen audio tracks and every subtitle, all in one box. The Matroska container: it will hold practically any codec ever made. That makes it the right destination when what you need is high-quality rips and archives with multiple audio and subtitle tracks.