There ya have it. The keys to Flutedom.

All us NYC boys and girls know that stuff.

Just kidding of course...... But Keith is spot on.
I'll review it again but for now I will add to the part about facial muscles. The smear, chin and grin muscles are all used together but some obviously, let me say, favor one or another.
His mention of the importance of your body's air systems role in its effect on tone quality..... Not talking about the air stream but the way the body holds the air. When it's time to blow for the $$$ we sit up straight or stand.
I did love his imitation of famous player's tone quality.
Pahud and Gallios are two more to listen to.
In the world of flute and classical literature there is no peak at the top of the playing field. It is a plateau.
That group is technically proficient!!!
A quality tone is within almost everyone's reach. The flexibility of hands and embouchure is a much harder and dedicated task.
I studied with a city boy who graduated Julliard in the '40s, studied with Arthur Lora, who took over for Barrere at Julliard, and who worked his magic flute in the world of opera and many other areas.
My teach was playing a steady gig in the early years on TV when live musicians were on air as his teachers had the Met/NYP etc gigs. Nice to be at the top of their call lists
Keith's mention of viewing from the side of a flute being played is also valuable. That's what you get when you study one on one..... or should I say with the right one.
The very front of the lips are most important as it does the work with it's and the jaws subtle movements.