In one embodiment, a system includes a video multipoint control unit (MCU) and an audio conferencing bridge, the audio conferencing bridge being operable to receive audio streams from audio-only and video endpoints, and to negotiate video sessions between each of the video endpoints and the video MCU. In response to detecting when one of the video endpoints is an active speaker, the audio conferencing bridge transmitting a dummy audio stream over a dummy audio channel from the audio conferencing bridge to the video MCU. The dummy audio stream causes the video MCU to switch an image in a video output stream. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure.