These are still working great for me, have a few of them in my house 
RTL_433 on an ESP32 or with an SDR
For the control a wifi relay
SDR is only a receiver and not a transceiver.
You can in other words not transmit a signal with it.
Indeed this is why I added “For the control a wifi relay”
Ahh, now I see what you meant with that line.
I took it as something in the video.
I should have added bullet points 
to differentiate.