A network-based system for live media broadcasting includes a server system including processing structure configured to: deploy processor-executable program code executable on a requesting client computing device for provisioning the requesting client computing device with a browser-based mixing user interface for selective mixing in the browser using at least one media stream received by the requesting client computing device from the server system to generate a mixed video stream and at least one associated audio stream; the processing structure further configured to: receive one or more live media streams from other client computing devices; stream media data from the one or more live media streams to the requesting client computing device over at least one live streaming media connection; and receive, from the requesting client computing device, the mixed video stream and the at least one associated audio stream. Various related systems, devices and methods are provided.