If the video doesn't work,
and view it in your favorite player.
Notice how as the trampoline pushes up(whilst feet are still in contact with the bed), the arms and shoulders start to turn. (See the red dots). The momentum from this carries the body around, combined with the looking for the other end of the trampoline.
To slow the turn down before landing the arms are brought back down to the sides as in normal straight bouncing. This has the same effect as in ice-dancing when skaters open-out in order to slow down a spin.
Safety is the most important thing to get right when trampolining
especially when learning new moves. Read more on the
trampoline safety page.