This instruction can to various degrees be extrapolated to other environments/locations.
I would add this suggestion. Stay out of line of door, or windows as much as possible. There is no need to be near door to talk to whoever knocked.
Although he never expressly says do not approach door, which he probably should, if you watch him when he actually shows what to do, he is never in line with door. Do not give a potential threat a direct line of attack.
You must account for entire geometry of your space. Account for angles!
Also if you have a camera and lights, and other equipment, such as motion detectors and intercom the threat will be less inclined to position you. It is perhaps a good idea to move to a position to thwart threat forced entry. It depends.
Also , having the phone ready to call 911 is a good idea. But automatically calling them is not ideal.
Don’t make call unless it is really required. Be reasonably sure.
Police response is dangerous in itself.