"Step four of Natural weave is virtical. What does it mean "virtical" do we stop and lower? If we don't stop then how can it be virtical. Sorry but I am confused by this as in the slow foxtrot there is continuity."
Not really step four of a natural weave as this figure doesn't include a pure weave action, as would constitute the bulk of an extended weave, or that you have on pair of steps of in the middle of a weave from promenade.
By vertical, the body is oriented vertically, moving horizontally, and the moving foot stays essentially under the shoulder. There is no incline of the whole body to reach the foot out from under the body, as is used on steps where swing creates a sway. Remember, unless the whole body is inclined, the moving foot has to stay under the body - you must never reach a foot by isolating it from your body. You parnter can only feel what your body is doing, so your foot placement must be predictable from your body action for a partner to be able to match it; also, many people who send their leg out in advance put it into their partner's space (in which they can feel what you are doing, but not in a usefull way).