The Media Gateway role is used by Genetec™ Mobile and Web Client to get transcoded video from Security Center. The Media Gateway role supports the Real Time Streaming Protocol (RTSP), which external applications can use to request raw video streams from Security Center.
There are many uses for raw (not decoded) video streams. For example, an external system can use the raw video streams to perform video analytics and trigger events. Another application can display video on a web page using an off-the-shelf viewer that supports the camera's specific encoding.