Wordpress Youtube embed autoplay and wmode=opaque filter

functions.php

<?php
add_filter('oembed_result', 'youtube_autoplay_filter', 10);

function youtube_autoplay_filter($iframe_html){
    $matches = array();

    if (!preg_match('~src="([^"]+?)"~iu', $iframe_html, $matches))
    {
        return $iframe_html;
    }

    $url = $matches[1];

    if (FALSE === mb_strpos($url, 'youtu'))
    {
        return $iframe_html;
    }

    $url_suffix = '';

    if (false === mb_strpos($url, '?'))
    {
        $url_suffix .= '?';
    }
    else
    {
        $url_suffix .= '&';
    }

    $args = array(
        'wmode'          => 'opaque',
        'autoplay'       => 1,
        'cc_load_policy' => 1,
        'rel'            => 0
    );

    $url_suffix .= http_build_query($args);

    $iframe_html = preg_replace('~src="([^"]+?)"~iu', 'src="$1' . $url_suffix . '"', $iframe_html);

    return $iframe_html;
}