Comment by EricE

Homekit doorbells use iCloud services and storage to host/serve the video; that's how Apple is involved even though they don't make the doorbells.

I had a Nest at my previous house - decided to try the Wemo Homekit doorbell this time and I'm very pleased with it. I also use an Apple TV to drive all the content on my TV and the Homekit video notifications are amazing - instantaneous since the Apple TV is my local homekit hub. Way faster and far more reliable than the Nest doorbell ever was.