Modify the allowed Video extensions on WP Vimeo Videos. Add this code to your theme's functions.php.

functions.php

<?php

/**
 * Modify the allowed extensions on WP Vimeo Videos
 * @return string[]
 */
function filter_dgv_allowed_extensions() {
	return array( 'mp4', 'mov', 'flv' );
}
add_filter('dgv_allowed_extensions', 'filter_dgv_allowed_extensions');