To do a vertical back roll, you're going to start in your hand roll with the hoop in front of you, rotating counter-clockwise. So, I've got my thumb up, my palm towards the left. Give it a push. My hoop is rotating counter-clockwise. I'm keeping it nice and strong in front of me, keeping my thumb out. Then, when the hoop touches your palm, you're going to give it a grab. Then, you're going to bend forward inside the hoop, allowing the hoop to then roll across your back, sticking your left arm in, grabbing as it comes across. And then, let go with the right and continue the hand roll on the left.
So let's switch back slowly once again. Grab, bend forward. Allow the whole hoop to roll across your back. Left hand grabs from the left side, continue your hand roll. A little bit quicker this time. Grab, roll, hand roll. Again.
And that's how you do a vertical back roll.