PHP: Get Vimeo ID

gistfile1

function get_vimeoid( $url ) {
	$regex = '~
		# Match Vimeo link and embed code
		(?:<iframe [^>]*src=")?              # If iframe match up to first quote of src
		(?:                                  # Group vimeo url
				https?:\/\/                  # Either http or https
				(?:[\w]+\.)*                 # Optional subdomains
				vimeo\.com                   # Match vimeo.com
				(?:[\/\w:]*(?:\/videos)?)?   # Optional video sub directory this handles groups links also
				\/                           # Slash before Id
				([0-9]+)                     # $1: VIDEO_ID is numeric
				[^\s]*                       # Not a space
		)                                    # End group
		"?                                   # Match end quote if part of src
		(?:[^>]*></iframe>)?                 # Match the end of the iframe
		(?:<p>.*</p>)?                       # Match any title information stuff
		~ix';
	
	preg_match( $regex, $url, $matches );
	
	return $matches[1];
}

Fix using https://regexr.com/393r3
Commented here http://www.patricktalmadge.com/2011/12/17/regex-vimeo-parser/