Sometimes, you/your visitors may download media files from your website/wordpress/web application and upon download, especially media files, the file doesnt paly, or in case of a video, it plays with no audio/plays audio with no video. The problem may be with the MIME type not specified or included in your account, hence you need to add it

MIME types relay information to the browser about how to handle file extensions. You can add MIME types to enable visitors’ browsers to handle new technologies as they come out. To add new MIME types to your web server, define a name, directory, and file extension that correspond to the MIME type

Below are the steps to to follow

Add a MIME type

To add a MIME type, perform the following steps:

Login to your Cpanel, and Click on the Mime type Icon Under Advance Panel

1. Enter the name of the file type’s handler in the Mime Type text box.
   • For example, application/cgi is the handler for the .cgi extension.
2. Enter the file extension in the Extension(s) text box.
   • A file extension is made of the letters after the dot (.) in a file name. For example, filename.fileextension.
3. Click Add.

Official List of Mime type is available here

Delete a user-defined MIME type

To delete a MIME type, perform the following steps:

1. Click the X icon under the Remove heading.
2. Click Yes to confirm that you wish to remove the MIME type.