It appears that the answer is in the use of RTSP. But I cannot get it to work.
The designated RTSP address is 192.168.1.33:4554/stream (in my case), but all I can get is a faiilure to connect. I have tried a range of different appracoaches - direct entry in browser; prefix with vnc://, prefix with rtsp://, using vnc applications, etc. No joy.
I am obviously dooing something wrong; but what?