If you found this file in a chat or a download folder, you can use a tool like MediaInfo to "look inside" the doll and see exactly what video resolution and audio tracks it contains without actually playing the file.
: Unlike basic video formats, an MKV is a multimedia container . It doesn't just hold video; it "nests" multiple audio tracks (different languages), several subtitle tracks, and even chapter markers all within one single file. AgADMgEAArfOsUQ.mkv
The name "Matroska" comes from the Russian , which are the famous nesting dolls that fit inside one another. This is the perfect metaphor for what an MKV file does. If you found this file in a chat