: For advanced users, you can use the command ffmpeg -i AgADGwcAAlMFqVU.mkv -codec copy output.mp4 to instantly change the container without re-encoding the video. To See What's Inside :
Depending on what you want to do with it, here are the most effective ways to proceed: :
: Use the HandBrake Open Source Transcoder to change the format while maintaining high quality.