Many times great players and teachers think they can just say anything and it's valid because they played on tour. Johnny Miller really put out a well done video 15 years ago that has very good info in it. You could not go wrong with it. Brandel has done.... Sheeeet. Kostis, with his swingvision breakdowns, has done more damage to golf teaching progress than anyone in history. His one book, I believe titled "the inside path to better golf" was close to legit, but was still only part of the story.
Bottom line is, if you don't keep learning then your doing a great disservice by opening your mouth, especially if you have a vehicle like television. I would be willing to bet these guys including Miller think they know it all. I thought I did about 6 years ago, but thankfully I have opportunities to use Trackman and I still guinea pig in front of my camera every chance I get. God bless the teachers who are still searching for answers and not relying on a method or info that worked for 20% of there students 10 years ago.
Sorry, had to vent.