If this is a long recording and you only need a specific clip:

: A command-line tool for advanced users to convert files instantly. Documentation is at FFmpeg.org .

The .mkv (Matroska) format is a "container" that can hold high-quality video, audio, and subtitles.

It looks like is a specific filename, likely generated by a screen recording or streaming software like OBS Studio or ShadowPlay , which use date and time stamps (Year-Month-Day Hour-Minute-Second) for names.

: This is the most reliable tool for opening .mkv files. You can download it at VideoLAN .