You aren't likely to survive or stay in the fight with a birdshot hit at typical HD distances of under 15'. That lead is acting like a slug (e.g. a cut slug) at that range. It's absolutely lethal, and is going to convince the perp this was a bad plan.
Birdshot can of course kill, but I will not use or recommend birdshot for life safety purposes*, and believe it to be irresponsible to do. Your video only reinforces that.
No one is arguing it will not make nasty wounds and can't kill readily, particularly at point blank range. Note, however, the platform used in your video is a 24" barrel with a modified choke at 3.3 yards. You can find ranges significantly greater than that in a typical apartment or even a master bedroom, and your end user might be using a cylinder bore with 18.5" barrel, all of which exacerbate the limitations of birdshot even further. At very real distances you may encounter (and not just at the end of a hall) birdshot will not reliably penetrate sufficiently to reach vitals from lateral angles, through shoulders or through extended forearms, nor will it necessarily result in a psychological stop on a person with altered mental status. You don't assume the optimistic outcome, even if that often is the outcome.
Overpenetration is absolutely
one factor that a person must consider when doing their due diligence, and depending on your circumstances may be of little consequence or great importance, so we should of course plan to mitigate that during our risk assessment, but within reason I cannot think of any situation in which that concern overrides the concern of effectively stopping the threat to the life of you or your family. Taking this analogy to pistols, the threat of over penetration or a miss killing a bystander exists
no matter where you carry your concealed carry firearm if you're in a populated area, do you recommending carrying loads that under penetrate in this scenario as well?
Contingent on patterning, a reasonable compromise in my eyes for a home defense is #4 buckshot, and I say that acknowledging that this may still over penetrate and kill someone in an adjacent room. *There are a select few "birdshot" loads that will penetrate in the 12" range even out to 20 yards, and these would be viable as well. They tend to be plated "BB" sized pellets, but are more esoteric and not typically available at common retail outlets.
I'm not trying to change your mind as you've obviously drawn your conclusions, I'm just providing my rationale for whatever that's worth to someone else reading this.
NOW, ASK those same "respected instructors " what they advocate for INSIDE a house where potential over penetration could be an issue?
What do police officers use inside homes, where over penetration remains an issue? Departments that still use shotguns train to swap from buckshot to slugs as the situation dictates, do you know of any that swaps from buckshot to birdshot? Why do you suppose that is?