Ipx-550.mkv.mp4

If you need to change the actual format (not just the name) for better compatibility, use a tool like Handbrake :

A flexible container that can hold unlimited video, audio, and subtitle tracks in one file. IPX-550.mkv.mp4

If you downloaded this file from an untrusted source, run a scan with Malwarebytes before opening it, as double extensions are sometimes used to hide executable scripts (e.g., video.mp4.exe ). If you need to change the actual format

The most universal video format, compatible with almost all devices and players. A file named appears to have two video container extensions

A file named appears to have two video container extensions.

Click Start Encode to create a clean, single-extension version.

This often happens if someone manually renamed the file or if a conversion process failed to replace the old extension. Usually, the last extension ( .mp4 ) is what your operating system will try to use. 2. How to Play the File If your media player shows an error, try these steps: