Well, i have to admit i'm very confused by all this. Perhaps i don't know what the expression "A frame" means.
Surely, when the left foot plants on step 2 of the natural turn (S waltz) the feet are well separated, and you will get what i assume is the "A frame" being refered to here.
For example, see Hilton's slow waltz on Youtube:
http://www.youtube.com/watch?v=HkItbQjX8eY&feature=related

What am i missing here?

THe expression "body weight" itself can be confusing. It's only when we're stationary, and not changing our position vertically or horizontally, that the force we feel through our feet and legs is our body weight. There's no easy way to explain these things. That's one of the difficulties in learning to dance well.