The Orinoco Flow is essentially
an extended version of the Weave, in which one ball is carried through a
two-in-one pattern twice in opposite directions. This longer arm flourish
requires an extra throw to be made, bringing the Orinoco Flow out of
familiar 423-variation territory. That being said it is still important for
you be very comfortable with the Weave before attempting this trick.
To begin learning the Orinoco Flow, start with two balls in your dominant hand and one ball in your non-dominant hand. Shift your non-dominant hand such that it is positioned directly above your dominant hand, and then with your dominant hand make a throw from the center of your body to the dominant side of your body (as if doing a regular two in one pattern). At the same time you will swing your non-dominant hand around in a half-circle such that it passes outside of and then under the ball your dominant hand just threw. As that ball peaks and begins to descend you will make a roughly identical throw from your dominant hand, clearing space for your dominant hand to catch the first ball. As this second throw is being made your non-dominant hand should have completed its half-circle and ended up at about the center of your body. You will then swing your non-dominant hand back around and under the second ball, such that your non-dominant hand ends up crossed over your dominant hand. You will then catch the second ball in your dominant hand.
Practice this on both sides. For the next step you are going to make a crossing throw from your dominant hand to the non-dominant side of your body before catching the second ball. At the same time you will uncross your non-dominant hand in a large circle such that it passes outside of the descending second ball and then over and around the freshly thrown third ball, coming to a stop on the non-dominant side of your body. You will then make a throw with your non-dominant hand from the center of your body to the non-dominant side of your body (as if juggling a two in one pattern), clearing space for you to catch the crossing throw made by your dominant hand. Your non-dominant hand will then catch the ball it threw.
As shown, practice this on both sides. Notice how the last throw is basically a mirror image of the the first throw; to juggle the full pattern simply repeat the arm flourish and accompanying throws, this time with the opposite hands. The Orinoco Flow is only difficult insomuch as it can take some time to figure out the arm motions—after that it is about as hard as the Weave.