I get a fair amount of questions about the King Swing on The Nose route. Here is a cool ad the guys at xRez made for the new free climbing book, which shows the King Swing really well. This pic is from a project xRez is doing that will show the whole Nose route like this. Super cool!
As for the swing (that's Roger Putnam swinging):
This is the best place to swing, and the move around the arete you see Roger doing is what is called the 'sideways mantel'. Roger had done the KS a bunch, so he knew to stop when his feet hit the tan band/dike below the Boot.
Tom Evans documents a lot of King Swings on the El Cap Report that tend to show the swinger a little lower, which is actually harder, and you takes longer as you have to tension under the roof on the arete, and do a couple free moves over to Eagle. What Roger shows in this picture is ideal - just hit the arete and keep pushing yourself sideways and you can walk right over to Eagle Ledge.