It's easy to see why golfers get frustrated, they are usually confused by different golf instruction.
I break down the golf swing into 3 parts
IMO, you really cannot argue the physics or the geometry. Those are 'laws' and there is no real room for debate on these laws.
However, the biomechanics are a different story because golfers are different and how one golfer's body moves and how they react to that movement will differ from many other golfers.
So the biomechanics of the golf swing are up for debate, but the physics and geometry are more or less set in stone.
I think if one were to approach the question 'how do you start the downswing', they would be best off looking at all good ballstrikers and seeing all of the possible scenarios of how those golfers move on the downswing. Then label it as 'here's the most common way these great ballstrikers started the downswing, here's some unique start downs, etc.'
What much of this video shows is what Homer Kelley warned against...learning mechanics from feel. As Homer Kelley put it so beautifully, one should learn feel from mechanics.
But instead, most of these instructors are not even getting into the real mechanics of the startdown move and instead are telling the viewers of what they should feel. The problem is that the instructor's feels that work for them may be completely different from what I feel or what Lee Westwood feels or what the once 20 handicapper and now scratch golfer feels.
So my suggestion is to get into the mechanics first. Explore the possibilities that all good ballstrikers use (remember, good ballstrikers are what matter, nobody cares what some ham-n-egger 8 handicapper does). Then suggest ways of practicing those mechanics and then suggest some feels that students have felt when they started to get the mechanics down. But, always stress that it's a suggestion and that the viewer needs to get the mechanics down and try to figure out what those mechanics feel like to them.
The most misunderstood part of The Golfing Machine is that it's a system built on feel and learning how to feel and that being an extremely importance concept to developing one's golf swing. Most get into the technical jargon and the mechanics, but neglect feel and how to feel. Both HAVE to tie in together to develop a good golf swing.