Imthink the guy in the video is focusing on the knocking because many dogs go bonkers when there is someone at the door. We live down a country track and there are seldom knocks at the door, so I am happy for Dylan to bark when there is someone there. So when I trained this command, I didn't do the knocking bit.
I had him sit in front of me, I had the treats and the clicker. I used the command Speak, along with the hand signal, and when he barked, I clicked and treated and gave praise. You have to watch like a hawk and do it immediately they bark. When he got that that I taught the command Quiet, with the hand signal of putting my finger to my mouth, like a shush gesture. If the dog is quiet, click and treat. Do this a few times a day, for short period as with other training, and they pick it up really quickly. The clicker is a real aid, it's the first dog I've used a clicker with, and it really reinforces everything quickly.
If it's easier with out the knocking as per the video, don't feel you have to follow it slavishly, adapt it to your own situation. Dylan will give a bark when there is someone at the door, he doesn't go demented like some dogs, so that isn't a problem for me. Big birds in the garden is though, pheasants, partridges and sometimes a hawk comes to try for the little birds. He will go ballistic trying to get through the patio doors, and I don't want that, so I make him sit and use the quiet command til he stops barking and scrabbling at the door. Each time my hand goes to the handle he starts again, so I just continue to keep him sitting and quiet until he stops barking when I go to the door handle. It takes a lot of goes
. Finally, when he is quiet I will let him out, and of course he goes rocketing round the garden having a bark, but the birds have gone by then anyway
The hand gestures are really good, if you have an appropriate hand gesture for all your commands it helps as the dog watches you. Dylan will bark and quiet just by hand gesture, and do other things Imhave taught him, with just a hand gesture and without a verbal command. This is useful if your dog ever goes deaf, as my last dog Milo did.
Hope this helps
Lesley and Dylan