The S-Mount as demonstrated in the video by MMA pioneer Erik Paulson is a very effective way to attack from the top position. He shows three armbar options from this position. Two on he far side and a falling back armbar on the near side.
The S-Mount is also a great way to transition to the Spider Web. Once you have a secure Spider Web you can then work for the Armbar with less chance that your opponent can escape.
The S-Mount is great when you have everything tight and your weight on your opponent's chest. Makes it very difficult for the person on the bottom to deal with when they have a someone basically sitting on their chest.
