The motion of the hands, at the transition, described in
'Such a Little Secret' by John W. Barrett, is very similar to the one explained by Michael Jacobs in his video –
'Golf Show Part 2 Impact Low Point'. Interesting that a tiny fleeting motion of the hands during transition, rather against intuition, is paramount for good golf.
Some paragraphs from the book to give an idea -
'' Of all the lines of direction made available by the ability of the arms arms hands at the top to move wherever they wish, that from the butt end of the rubber grip straight down to the ball is the favorite of millions. It is as destructive as a dozen other equally erroneous lines of directions, all of which carry the hands and clubhead to the front of the player too early.
Assuming that the backswing has been completed to the best of the player's ability, the direction in which the hands must be guided is exactly that in which the end of the rubber grip is pointing when at the top of the backswing.
There must be no conscious effort, only guidance in the direction indicated by the end of the grip. It should certainly not be pointing at the ball and for the first couple of inches will not necessarily be pointing in the downward direction.
On no account must the butt end be thrown from the top down along a direct line to the ball or anything approaching it.''