Yeah her channel is so worth subscribing to! I love her training approaches.
My four dogs run toward the front hallway anytime the front bell goes or someone knocks, barking away -- but because I have always told them to wait outside the hall door, and always sent them out and closed the door to my 'dog airlock' before opening the front door, they have 'trained themselves' to know they can run UP to the hall and bark away (I like the canine warning/security system! ) but they never, ever enter the hall itself any longer in this particular situation --when I open the front door to answer to a caller. I always praise them for waiting outside before I close the hall door. To reinforce this, I could treat right upon re-entering the room (eg keep a little treat bag near the front door to always reinforce good desired behaviour).
I found this very interesting -- that the dogs had self-learned to wait simply because this behaviour was regularly reinforced and that all four respect the boundary line of the hall. If I had an open area before the door and no hallway, I might mark out a floor area in tape and train the dog(s) never to cross it without permission -- to always sit at that tape line and wait to be attached to a lead and released to walk forward and out the door. All sorts of possibilities but this does all take daily practice, positive reinforcement, constant practice, and family support at every level.
One thought -- if there is a back gate maybe make the front door off limits to ALL for entry/exit except on special occasions and have kids go through a back gate that has an automatic spring-closure mechanism -- and they only can go out when they are absolutely sure Sparky is not outside. But I'd do this in conjunction with training desired front-door behaviour for Sparky too.