A simple PHP function to parse a given string for a YouTube or Vimeo link (or embed code) and extract video ID, provider, etc.

function-parse-video.php

<?php
/**
 * Parse a video string
 *
 * @param string $haystack The string to be parsed
 * @param string $protocol The protocol to be used for the urls
 * @return array $video
 *
 * @version 2014-08-22
 * 
 * @author Poellmann Alexander Manfred, http://vendocr.at/
 * @copyright Copyright 2014 vendocrat. All Rights Reserved.
 * @license MIT License
 */
function vendocrat_parse_video( $haystack = '', $protocol = 'https' ) {
	if ( empty($haystack) )
		return;

	// make sure quotes (") are quotes and not enceded
	$haystack = stripslashes( trim($haystack) );
	$haystack = htmlspecialchars_decode( $haystack );

	// check for iframe to get the video url
	if ( strpos( $haystack, 'iframe' ) !== false ) {
		// retrieve the video url
		$pattern = '/src="(.*)?"/isU';

		if ( preg_match( $pattern, $haystack, $matches ) ) {
			$link = trim( $matches[1] );
		}
	} else {
		// we already have a url
		$link = $haystack;
	}

	// return if no link given
	if ( empty($link) )
		return;

	// prepare some vars
	$provider  = '';
	$video_id  = false;
	$video_str = '';
	$thumb_str = '';
	$image_str = '';

	/*
	 * Pattern tested on
	 * https://www.youtube.com/watch?v=M0jmSsQ5ptwhier
	 * https://www.youtube.com/v/M0jmSsQ5ptwhier?fs=1&amp;hl=en_US
	 * https://www.youtube.com/embed/M0jmSsQ5ptwhier
	 * //www.youtube.com/embed/M0jmSsQ5ptwhier
	 * https://www.youtube.com/watch?v=M0jmSsQ5ptwhier
	 * http://player.vimeo.com/video/37985580?title=0&amp;byline=0&amp;portrait=0
	 * http://vimeo.com/37985580
	 */
	$pattern = '@(http:\/\/|https:\/\/|\/\/)?(www|player)\.?(youtube|youtu|vimeo)\.(com|be)?\/(watch\?v=|v\/|embed\/|video\/)?([a-zA-Z0-9-_]+)@im';

	if ( preg_match( $pattern, $haystack, $matches ) ) {
		$video_url       = $matches[0];
		$video_protocol  = $matches[1];
		$video_subdomain = $matches[2];
		$video_domain    = $matches[3];
		$video_tld       = $matches[4];
		$video_param     = $matches[5];
		$video_id        = $matches[6];
	} else {
		return false;
	}

	// check protocol
	if ( $protocol != 'http' AND $protocol != 'https' ) {
		$protocol = 'https';
	}
	$protocol.= ':';

	// YouTube
	if ( strpos( $video_domain, 'youtu' ) !== false ) {
		$provider = 'youtube';
	
		$video_str = $protocol .'//www.youtube.com/watch?v=%s';
		$thumb_str = $protocol .'//img.youtube.com/vi/%s/2.jpg';
		$image_str = $protocol .'//img.youtube.com/vi/%s/0.jpg';

	// Vimeo
	} elseif ( strpos( $video_domain, 'vimeo' ) !== false ) {
		$provider = 'vimeo';

		$video_str = $protocol .'//player.vimeo.com/video/%s';

		// try to get the thumbnail
		try {
			$hash = unserialize( @file_get_contents( "$protocol//vimeo.com/api/v2/video/$video_id.php" ) );
			if ( ! empty($hash) AND is_array($hash) ) {
				$thumb_str = $hash[0]['thumbnail_small'];
				$image_str = $hash[0]['thumbnail_large'];
			}
		} catch ( Exception $e ) {}
	}

	// set up arguments
	$args = array(
		'id'       => $video_id,
		'provider' => $provider,
		'url'      => sprintf( $video_str, $video_id ),
	);

	if ( $thumb_str ) $args['thumb'] = sprintf( $thumb_str, $video_id );
	if ( $image_str ) $args['image'] = sprintf( $image_str, $video_id );

	// parse arguments
	$defaults = array(
		'id'       => false,
		'provider' => false,
		'url'      => false,
		'thumb'    => false,
		'image'    => false,
	);
	$video = array_merge( $defaults, $args );

	return $video;
}
?>

Not working for this URL: https://vimeo.com/91993392