From above.
Rossi does seem to get credit for the Rossi dangle. I watched a video from a guy trying to explain the purpose. He qualified as an expert, as he had a Euro accent, and was more the 60 miles away. But he failed to talk about pressure from the outside knee, or foot peg pressure, or much of any use. Some of these guys have some useful info, but it lacks much deep understanding IMO.
The first secret about going fast on a track is the fit of the bike. 3 things: the forward thrust from braking, which is stopped by the gas tank. The rear thrust from acceleration which is stopped by the rear tail piece. The fit of the knees around the tank which mostly aims the bike. Lower seat height helps, and the fit of the bars and pegs. Take two identical bikes, one in cruiser riding mode, one with the fit from above, and notice the difference.
For cross country dirt bike riding, and riding at tracks like the Isle of Man. When the bike gets lose, it is usually because the knees are not clamped to the tank. It comes from getting tired. The IOM style of riding is different than the course track riding. We should ride more like the IOM guys IMO, as we too are on the street. Limited bum movement, looking forward, head over the elbow or wrist depending on your shape. Some necks bend differently than others. Most of these modern GP riders are 5' 8" and slim. They tuck in better than many of us.
Some bikes like my SV1000S fit me, partly because I knew what I was looking for. I did raise the bars an inch or so as I have short arms. I lowered the seat height as I have ducks disease too. So this thing goes where I want it to, mostly from body steering.
My Yamaha's do not fit the same way. They are the common sit up style, and the gas tanks are narrow at the back. They do not respond to body steering nearly as well, so the riding style has to change.
All the modern tracks that the GP riders are on, coupled with the modern tyres and brakes, allow these guys to hang off the sides, which they need to do to go fast.
A ride on a set of gumballs is staggering for grip, compared to the tyres we use on the street. But now the bikes make so much power they can shred a set of soft tyres.
Definitely watching IMO. Same with the IOM.
UK
