Verify whether a YouTube video exists using PHP and oEmbed status codes. Instead of actually fetching the video’s URL using a tool suchas a cURL, we can speed things up by just checking the response headers by using PHP’s get_headers() function. Full article: https://imelgrat.me/json-xml/oembed-protocol-embed-videos-news/

check-youtube-id.php

<?php

	/**
	 * @author Ivan Melgrati
	 * @copyright 2018
	 */

	function YouTube_Check_ID($videoID)
	{
		$is_valid = true;

		// YouTube oEmbed API endpoint (https://www.youtube.com/oembed)
		// Query it using the video's URL as parameter
		// The "format" parameter may be either JSON or XML. Not relevant for this tes.

		$theURL = "http://www.youtube.com/oembed?url=http://www.youtube.com/watch?v=$videoID&format=json";

		$file_headers = @get_headers($url);
		if ($file_headers === false)
		{
			$is_valid = false; // when server not found
		}
		else
		{
			foreach ($file_headers as $header)
			{
				// Parse all headers. Corrects $url when 301/302 redirect(s) lead(s) to 200:
				if (preg_match("/^Location: (http.+)$/", $header, $m))
				{
					$url = $m[1];
				}
				
                // Use regex to detect HTTP response codes 
				if (preg_match("/^HTTP.+\s(\d\d\d)\s/", $header, $m))
				{
					$code = $m[1];
				}
			}

			// $code 404 This must be a bad video ID.
			if ($code == 404) //
			{
				$is_valid = false;
			}
		}

		return $is_valid;
	}

	$id = 'BKorP55Aqvg'; //Video id goes here

	if (YouTube_Check_ID($id))
	{
		echo "Yes! The video exists";
	}
	else
	{
		echo "Oh, no! The video code is wrong and it can't be found on YouTube";
	}

?>