The backward facing Hyper, or Backside-Hyper, is useful for vanishing into gainer and cork axis tricks. In this scenario, the inside leg, which is usually the swinging leg for such tricks, lands first, followed the outside leg. As they both land, the inside leg is then lifted straight up, and the performer leans back into the flip, creating a vanish transition. It should be remembered that vanish corks or gainers are not unique tricks, but a novel transition into them. The point of takeoff in these tricks is identical for swingthroughs from a complete stance, or vanishes from a hyper stance. This concept is further discussed here.
Similarly, tricks like aerials and btwists utilize a similar movement, but allow the performer to further pivot on the ground to maintain their momentum line, as seen in the video above. Vanishing into vert kicks from the hyper landing is identical to this method of vanishing, but without inverting. By landing on the inside leg, a vanish is performed with a swing takeoff, and the performer remains upright. Because an Inside-Hyper is usually preferred for this, many trickers tend to cut their swing takeoffs short, ending at the target, to more closely mimic a typical swing takeoff position, and maintain the usual in-air rotation.