Haha @Crim it's funny you brought up that video. The last two weeks I've been studying it a bit with the help of analyzr. Definitely a cool look.
With this view, it's interesting to see his knees square up in the early downswing, which then leads to the extension pieces starting to kick in, and the right foot banking. Plus it's cool to see just how long he keeps the hitting area in his central vision.
I think this is one area where most mid to high handicappers can improve. Too many golfers pick their heads up very early, many times before they have even hit the ball!
Yea I've never been a fan of the "keep your head down" stuff because it's so vague, but since you and I both seem to know what it really means, doing it correctly allows the shoulders and back to turn and extend at the correct rates. Just better sequencing all around as long as the lower body is driving forward, up, and around like it should be.
Of course, it's not 100% the same for everyone as Annika had her own special way of doing it too, for example, so... but I do love the way Tiger executes these series of pieces for sure.