Mini plugin to center Youtube iframes inserted with oEmbed in WordPress

center_youtube_iframe.php

<?php
/**
 * @package Uploads_Media
 * @version 0.1
 * @see http://wordpress.stackexchange.com/a/50781/16301
 */
/*
Plugin Name: Center Youtube Iframe
Plugin URI: https://core.trac.wordpress.org/ticket/32920
Description: Wraps youtube iframe in a centered paragraph
Author: Jesus Franco
Version: 0.1
Author URI: https://tzkmx.wordpress.com/
*/
add_filter( 'embed_oembed_html', function( $cache, $url ) {
    if( preg_match('/youtube.com/', $url) ) {
        return '<p style="text-align:center;">' .$cache . '</p>';
    }
    return $cache;
}, 13, 2);