01. - Mom And Daughter.mkv.mp4

Remove the extra .mkv or .mp4 so only one remains (e.g., 01. Mom And Daughter.mp4 ). Select the file and press Command + I to "Get Info." Under Name & Extension , delete the unnecessary extension. 4. Convert if Unplayable

A free tool to convert MKV to MP4 (or vice-versa) properly without just changing the name.

Check the box for to see the full name. Right-click the file and select Rename . 01. Mom And Daughter.mkv.mp4

The is always the one at the very end. In this case, your computer sees it as an MP4 file . However, if it was originally an MKV and someone just typed ".mp4" at the end, it might not play correctly in standard players. 2. How to Play the File

If renaming the file doesn't work and it still won't play, the "wrapper" might be broken. You can "remux" or convert it to a standard format: Remove the extra

Drag the file into a Google Chrome tab. Chrome has built-in support for many common video codecs and may play it directly. 3. Fix the Filename (Remove Double Extension)

Because of the potential format confusion, it is best to use a "universal" media player that can handle almost any codec. Right-click the file and select Rename

If you have OBS installed, you can use the Remux Recordings tool to quickly change the container format from MKV to MP4 without losing quality. Summary Table Recommended Tool/Action Play immediately VLC Media Player or MPV Fix name Rename file (ensure "File name extensions" is on) Change format Use HandBrake or CloudConvert