/**
 *
 * Add custom post types to data source
 *
 * @param array $post_types
 *
 */
add_filter( 'streamtube/core/widget/posts/post_types', function( $post_types ){

    // Define your own custom post type
    $custom_post_type = array(
        'custom_post_type_slug'    => esc_html__( 'Post Type Name', 'streamtube-child' )
    );

    return array_merge( $post_types, $custom_post_type );

}, 10, 1 );