A file named appears to have two video container extensions.
Click Start Encode to create a clean, single-extension version. IPX-550.mkv.mp4
If the file won't open, it may be corrupted or a "fake" file (common with oddly named downloads). Right-click the file, select Properties , and check if the file size matches what you expect for a video. 3. Fixing the Extension A file named appears to have two video container extensions
Download VLC Media Player or MPV . These players ignore extension errors and read the "magic bytes" inside the file to determine how to play it correctly. IPX-550.mkv.mp4