This page covers a variety of tricks involving a flyer on the bottom level making a pass from one fly bar to the other. As they leave their first bar, a second flyer drops down from the top level to catch the bar they just left.
The example shown in the first video below involves the first flyer making a Planche passage across the bottom (Trick ID: 021) while the top flyer does a 'Drop from Top Level' (Trick ID: 549).
You can find out more about this trick in my books:
Thanks to the flyers of La Nouba.