The "mkv" in mkvcinema..com refers to the Matroska Multimedia Container. Unlike proprietary formats, Matroska is an open-standard, free container format that can hold an unlimited number of video, audio, picture, or subtitle tracks in one file.
: MKV files can host "soft" subtitles, which can be turned on or off, rather than "hard-coding" them into the video frames. mkvcinema..com
: In regions with limited internet bandwidth, downloading a compressed but high-quality MKV file is often more practical than attempting to stream in 4K. The "mkv" in mkvcinema