Chrome supports its own streaming method, MPEG-DASH with H.264 which is what Youtube runs on where possible. Firefox stated it won't support H.264 on principle (although it does now, for WebRTC). Android supports HLS, as does iOS, out of the box. HLS was designed to supersede RTSP however we also have the equally-ubiquitous RTMP, which Flash supports natively. You can get an HLS stream via Flash with an add-on to some clients so now this will work on IE, Chrome Firefox, and there are also some custom, proprietary clients out there for h.264/HLS. It's not a pleasant ecosystem right now..