youtube-video.sass

video_youtube.css

.video {
  position: relative;
	padding-bottom: 56.25%;
	padding-top: 25px;
	height: 0;
}

.video iframe {
  border: none;
  position: absolute;
  top: 0;
  left: 0;
  width: 100% !important;
  height: 100% !important;
}

video_youtube.php

<div class="video"><iframe src="https://www.youtube.com/embed/iNPE0zGucTo" allowfullscreen></iframe></div>

<?php
// Типы превью
// http://shpargalkablog.ru/2013/06/youtube.html

// Если iframe
$iframe_video = (string) trim(get_field('youtube'));
preg_match( '/[^>]*src *= *["\']?([^"\']*)/i', $iframe_video, $matches );
$video_src = $matches[1];

$params = parse_url($video_src);
$code_video = explode('/', $params['path'])[2];
    
// Если ссылка на ролик
$params = parse_url(get_field('link'));
parse_str($params['query'], $query);
$link = explode('/', $params['path'])[2];
$query['v'];

//Универсальный вариант
$subject = "http://www.youtube.com/watch?v=z_AbfPXTKms&NR=1";
preg_match('%(?:youtube(?:-nocookie)?\.com/(?:[^/]+/.+/|(?:v|e(?:mbed)?)/|.*[?&]v=)|youtu\.be/)([^"&?/ ]{11})%i', $subject, $matches);
$matches[1];

video_youtube.sass

.video
	position: relative
	padding-bottom: 56.25%
	padding-top: 25px
	height: 0
	iframe
		border: none
		position: absolute
		top: 0
		left: 0
		width: 100% !important
		height: 100% !important