WordPress at a glance
filter is not described

media_upload_mime_type_links filter-hook . WP 3.1.0

Filters the media upload mime type list items.

Returned values should begin with an <li> tag.

Usage

add_filter( 'media_upload_mime_type_links', 'filter_function_name_1121' );
function filter_function_name_1121( $type_links ){
	// filter...

	return $type_links;
}
$type_links(array)
An array of list items containing mime type link HTML.

Where the hook is called

media_upload_type_form()
wp-admin/includes/media.php 2445
echo implode(' | </li>', apply_filters( 'media_upload_mime_type_links', $type_links ) ) . '</li>';

Where the hook is used (in WP core)

Does not used.