system
A chat on subreddit /r/NoStupidQuestions
human
It’s unlikely that the dog conflated the images on a flat screen with the noise.

Where was your dog before he was your dog? If he was raised in a house or business, he’s probably seen other dogs exhibit the behavior.
gpt
We bred this dog on our own, it has never been around a doorbell.  The dogs parents are still alive and even they dont run to the door for a doorbell noise.