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];
}