If you have landed on this page, you are likely frustrated. You have downloaded a file labeled "heyzo1122" (often associated with specific high-definition content releases), but it refuses to play correctly. Perhaps the video is stuttering, the audio is out of sync, there is no video at all (only sound), or the file won't even open in your default media player.
Look at the file extension. If it is .mkv instead of .mp4 , the fixes above still apply—just ensure your player (like VLC or MPC-HC) supports Matroska containers, which all modern ones do.
Happy viewing, and may your playback be smooth and your audio in sync.