I watched the Harrington grip video last week and it was a great refresher. I like you he illustrates how to use the middle two fingers of the trail hand to pull the lifeline of the trail hand down over the thumb. That was very helpful for me.
I also love the visual of the right hand being palm open and alongside the club and matching the clubface. That is a great reference in therms of how to rotate the trail hand to its correct orientation.
This is also a great video showing how the trail hand orientation will influence the path back in the takeaway.
http://www.youtube.com/watch?v=oR4gikihXG4?si=0WzL3so4dSN9fkXE&t=104