I have created a system capable of streaming video in real time in SL, I mean that all people see exactly the same thing regardless of when they activated media, exactly as it happens for audio streaming.
A recent version SL viewer is required (tested with the official viewer, Firestorm and Black Dragon). The installation of any software or plug-in on the PC is not required and there is no need to use any script in SL, simply set the parameters of the media in the parcel and the video will be displayed on all surfaces that use the set texture.
I have been using this system successfully in