I know what would happen with mine as it happens all the time in my house.

Ben would just say hello, Copper would fetch the person a ball and Jet would fetch them a bit of vet bed

Although maybe if the person was acting in an alarming manner they might act differently, who knows!

We had a situation like this not long ago. I organised a social weekend for Estrela people and we were having a meet up in the cabin one evening. The dogs had met everyone on the campsite and were happy to accept them. What I didn't know was that one of the people had brought his mate along for the evening. When he walked into the cabin Rio went nuts. Luckily there were a lot of people and she was intercepted before reaching the poor guy but I have no doubt he would have got a nip. Rio's technique is to rush barking and nip at trousers to keep her victim pinned to the wall. None of the other dogs in the cabin reacted like this. My male Estrela Dan is noisy but will run and hide. Rio is the only one of mine that will guard, but I don't think she would actually carry out any kind of sustained attack.

My friend told me...''Bruce didn't attack he just bared his teeth and stood his ground, everytime I tried to step in I heard a very low but meaningful growl''..... I asked what the others did, she said...they just sat there

I had to laugh at that golden retriever, what a complete tart

I really do not know what mine would do, they have no negative humans in there life ..

That was interesting.
I did notice that most of the dogs didn't 'watchdog' bark. Dogs that do alert at everything are often considered a nuisance so the trend is to train them out of it, or at a more basic level, select less noisy dogs.

I remember years ago someone I worked with had a Cavalier, and they were burgled one night but the barking of the dog woke up the household, and the intruder fled.

Merlin is too much of a watchdog at times, giving me a running commentary on whatever goes on outside. People at the door, he goes beserk at. But once I open the door he is ready to greet them. I have no idea how he would behave if they were uninvited and daft enough to brave his impressive display behind the door. I suspect he would bite, but who knows?

Rue, our rescue Malinois, who has been bite trained in her past, is not in the least bit guardy and seldom barks. She is very inhibited a lot of the time, as if she's had free-thought trained out of her. I don't think she would guard unless specifically told to, and we have no need of that.

My gardener has no such problems but he comes in through the front door let in by me first thing though he uses the side gate afterwards, All the dogs I've owned since he started coming treat him as a person who will play ball with them & often spend the whole day out with him if he is in the back garden. However my lawn is mowed every week by a different man & some of my dogs have objected to him as he comes straight round the back. Not my present bitch though she gives a short bark when he drives onto the drive but stops as soon as he starts the mower engine up,

Axel would hide, no doubt about that. He's got no guarding instinct at all and doesn't bark at people coming to the house.
Very interesting video.

SB what signage do you have? I think that would be an ace idea here

What do you mean by "negative humans"?