Wireless doorbell to latching ON/OFF Switch

I would like to use a wireless doorbell I have to control a latching ON/OFF Switch, I found this great video
My receiver circuit is slightly different as it has a CD4069 but I believe it won't matter as the wires going to speaker are used.
The schematic is not clear on the part where the 2 circuits are connected together, I can see a transformeless 220V AC to 12v DC circuit is used to power the latching circuit, does is it need an optocoupler, or speaker wires could be connected directly to the latching circuit ?

What is the power source for the doorbell receiver/sounder? I've seen both battery-powered and line powered. If battery, there probably is no need for an optocoupler.

ak

Thanks for your reply, each circuit has it's own line powered source (transformer less) 5V for the receiver/sounder, 12v for the latch circuit as it has a 12v relay as shown in the video.