I am very pleased that it work.
Did take some time to get it working and figure out how to do it.
it started a few weeks ago and installed the Xiaomi Fang camera at the front door with the fang hack.
I was able to sent a picture to the phone when the bell was pressed.
For the camera to work not only with the rtsp stream but also with image.jpg i needed a different hack.
Some french info about this one http://domo-attitude.fr/camera-xiaomi-xiaofang-flux-jpg-domoticz-jeedom/
But i did not want to look on the phone when watching the tv.
I already have a chrome cast on the Onkyo receiver and a LG tv.
I have created 3 flows to get it working.
1e one is just for the doorbell itself to send a picture
Here the picture is send.
I made (copied) a HTML page where image.jpg is refreshed every second or so and i stream this to the chrome cast.
And the flow for the camera to tv
Here is a video how it looks like