DEVICE FOR MANAGING THE INSERTION OF COMPLEMENTARY CONTENT INTO MULTIMEDIA CONTENT STREAMS The invention pertains to the transmission of multimedia content to communication terminals by multimedia content transmission infrastructures. Here, "multimedia content" refers to a set of data of the same type, such as television or radio programs, potentially advertisements, data files, or audio or video files. Furthermore, here the term "multimedia content transmission infrastructure" refers to either a communication networl< or a broadcast networl<. Finally, here the term "communication terminal" refers to any fixed or mobile (or portable or cellular) communication device that is at least capable of receiving multimedia content from multimedia content transmission infrastructure (potentially radio). Consequently, it may, for example, be a land-line or mobile (or cellular) telephone, a desktop or laptop computer, a personal digital assistant (or PDA), a multimedia content receiver (for example, a decoder, a residential gateway, or a STB (set-top box)), provided that it is equipped with communication means, which are potentially radio-or satellite-based, that can receive multimedia content. The multimedia content is generally transmitted to the receiving communication terminals in an ordered (i.e. time-scheduled) manner within the stream. Once a stream's programming has been established, that stream's multimedia content is respectively associated with set intervals of time. It is then difficult to modify the stream's programming, for example to replace (or substitute) multimedia content that must soon be transmitted with other multimedia content, or to insert (multimedia) content between two pieces of multimedia content that must soon be transmitted. Thus, such a modification could prove interesting, particularly in the field of advertising, for example, in order to be more flexible or responsive (as a result of instant knowledge of audiences). The purpose of the invention is therefore to make it possible to manage the insertion and replacement of multimedia content within streams. To that end, it discloses a device devoted to managing multimedia content that must be transmitted to communication terminals, and comprises management means tasked, in the presence of a multimedia content stream to be transmitted, with determining in real time (dynamically) complementary content (additional and/or substitute content) to be inserted in selected locations of that stream, from among a set of pieces of complementary content each associated with a predefined profile, and potentially at least partially contained within the stream, and based on at least one criterion dealfng witfi at least part of the profiles, these management means potentially being tasked with determining the complementary content to be inserted based not only on at least one criterion dealing with at least part of the profiles, but also based on information representative of the "approximate numbers" of users who at a given moment are using some of the stream's multimedia content (i.e. based on the instant audience data). The device for managing multimedia content that must be transmitted to communication terminals comprises management means configured, in the presence of a multimedia content stream to transmit, to determine iri real time the complementary content to be inserted at chosen points in said stream, from among a set of complementary content each associated with a predefined profile and potentially at least partially contained within said stream, and based on at least one criterion dealing with at least one part of said profiles, said management means being configured to determine said complementary content to be inserted based on at least one criterion dealing with at least part of said profiles and information representative of the "approximate numbers" of users who at a given moment are using some of said stream's multimedia content. The inventive device may comprise other characteristics which may be taken separately or in combination, particularly: these management means may be tasl