Some clarifications about the platform you can use:
You need to use a Flash video chat application that integrates with PHP and a RTMP server where users can connect and interact live.
PHP scripts just generate pages from server while clients need to stream their webcams live to other users with a persistent connection.
There are also some limited solutions using HTML5 JS, P2P, AJAX but these don't work on main browsers (IE, Safari..) and are not reliable as using Flash and a RTMP server that works for most users.
Sample PHP Webcam Video Chat solutions: