Mediator for optimizing the transmission of media contents between a multimedia resource function and a plurality of terminals

A mediator for the transmission of media contents includes means for receiving video content requests from terminals when they request to take part in said video call conference, and for optimizing these requests, in order to avoid requesting any redundant video stream from a multimedia resource function, before forwarding the optimized requests to the multimedia resource function; means for implementing virtual conferees as a function of the video content requests from said terminals, for receiving the video streams that have been requested by the optimized request, from the multimedia resource function, and then forwarding the received video streams to the terminals that have requested them, in a broadcast way when a same video stream has been requested by several terminals, and means for commanding the telephony server to accept the implemented virtual conferees in the video call conference.