Surfing the web i found VideoWhisper that develop 2 softwares both free and commercial editions: VideoConference and LiveStreaming. Most interesting part is that they are available as “standalone” PHP, Joomla module or WordPress plugin; an online demo available for both. The first allow to create multiple video chat using AS3 technology. The limitations of free version are: max 4 rooms, max 10 users for room, one video stream slot is used to display a free edition ad, maximum number of simultaneous videos streams viewed 2.
Live Streaming allows to create broadcast sites like Justin TV, Mogulus. The limits of free version are: 10 max number users for each stream, trial ads on all interfaces, starting trial message on chat interfaces .