Extend Ultimate Member File Upload types

um-upload-video.php

<?php
/**
 * Issue: Cannot upload video using file upload form fields – no mp4 option!
 * @since 2019-05-21
 */
function um_add_more_allowed_file_types( $allowed_types ) {

	if( is_array( $allowed_types ) ) {
		$allowed_types = array_merge( array(
				'3gp'	 => '.3gp - 3GPP video',
				'avi'	 => '.avi - AVI video',
				'mkv'	 => '.mkv - Matroska video',
				'mov'	 => '.mov - QuickTime video',
				'mpg'	 => '.mpg - MPEG-1 video',
				'mp4'	 => '.mp4 - MPEG-4 video',
				), $allowed_types );
	}

	return $allowed_types;
}
add_action( 'um_allowed_file_types', 'um_add_more_allowed_file_types' );