Get The Youtube ID from a Youtube URL in the contents of a WordPress Post

get_youtube_id.php

<?php
function catch_youtube_url() {
	global $post, $posts;

	ob_start();

	ob_end_clean();

	$youtube_url = '/https?:\/\/(?:www\.)?youtu(?:\.be|be\.com)\/watch(?:\?(.*?)&|\?)v=([a-zA-Z0-9_\-]+)(\S*)/i';
	$url = preg_match($youtube_url, $post->post_content, $matches);
	if ( $matches ){
		return $matches[0];
	}
}
$video_link = catch_youtube_url();
parse_str( parse_url( $video_link, PHP_URL_QUERY ), $my_array_of_vars );
echo $my_array_of_vars['v'];