/* 
	 * Retrieve the video ID from a YouTube video URL
	 * @param $ytURL The full YouTube URL from which the ID will be extracted
	 * @return $ytvID The YouTube video ID string
	 */
	function getYTid($ytURL) {
		
		$ytvIDlen = 11;	// This is the length of YouTube's video IDs
		
		// The ID string starts after "v=", which is usually right after 
		// "youtube.com/watch?" in the URL
		$idStarts = strpos($ytURL, "?v=");
		
		// In case the "v=" is NOT right after the "?" (not likely, but I like to keep my 
		// bases covered), it will be after an "&":
		if($idStarts === FALSE)
			$idStarts = strpos($ytURL, "&v=");
		// If still FALSE, URL doesn't have a vid ID
		if($idStarts === FALSE)
			die("YouTube video ID not found. Please double-check your URL.");
		
		// Offset the start location to match the beginning of the ID string
		$idStarts +=3;
		
		// Get the ID string and return it
		$ytvID = substr($ytURL, $idStarts, $ytvIDlen);
		
		return $ytvID;
		
	}

/* 
	 * Retrieve the video ID from a YouTube video URL
	 * @param $ytURL The full YouTube URL from which the ID will be extracted
	 * @return $ytvID The YouTube video ID string
	 */
	function getYTid($ytURL) {
		
		$ytvIDlen = 11;	// This is the length of YouTube's video IDs
		
		// The ID string starts after "v=", which is usually right after 
		// "youtube.com/watch?" in the URL
		$idStarts = strpos($ytURL, "?v=");
		
		// In case the "v=" is NOT right after the "?" (not likely, but I like to keep my 
		// bases covered), it will be after an "&":
		if($idStarts === FALSE)
			$idStarts = strpos($ytURL, "&v=");
		// If still FALSE, URL doesn't have a vid ID
		if($idStarts === FALSE)
			die("YouTube video ID not found. Please double-check your URL.");
		
		// Offset the start location to match the beginning of the ID string
		$idStarts +=3;
		
		// Get the ID string and return it
		$ytvID = subtr($ytURL, $idStarts, $ytcIDlen);
		
		return $ytvID;
		
	}

This code allows you to retrieve the 11-character ID string from a YouTube video URL.

Retrieve YouTube video ID from a YT URL

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