I may have started one of those topics the OP is referring to. I was seeking advice on getting a single mother into the world of home defense, so I'm probably not the person to add much insight. But here are my thoughts anyway.
In the post I mentioned above, I stated that I could let my friend try out some of my guns and show her the basics of how they operate. But I have guns primarily for hunting and recreational shooting-not defense, and I'm not qualified to teach anything about tactics.
I have a couple of the Thunder Ranch videos, and I think there is definitely some value in them. They typically start by addressing situational awareness, weapon choice (to a small extent), preventing/avoiding conflicts, and addressing perspectives on things such as what a bad guy might do or how he might react to your actions. This information is good for anyone to hear, and I suspect this can be nearly as valuable in video form as it would be in person.
Where I think an in-person class would really help is teaching proper and efficient handling and operating a weapon in a life threatening situation, where it's hands-on and you can get immediate and individualized feedback. It is also a place to be corrected if one has misconceptions about any number of things. But I suspect that even experts and professionals have their own biases. Clint Smith, for example, is often quoted as saying something about how the purpose of a pistol is to get to the rifle or shotgun you should have had in the first place. Many others would strongly disagree with that statement. So I don't know that all professional instructors necessarily meet the individual needs of everyone.
I would think a little bit of everything might be the best route. Books and videos can help establish a proper mindset and prepare a person for hands on learning. Then in-class instruction (maybe from a couple different instructors?) can teach the physical aspects and correct errors in thinking and form. After that, practice with friends/relatives may help cement learned skills and keep them sharp.