It starts from back control: seatbelt control, two hooks in, rider's back on the ground. As a reference for right/left side, I'll follow the Gi match; I'll give instructions as if I were Keenan's coach.
Lay on your left side, so you can trap the holding arm and turn away from the choking arm. In the meantime, grab the choking wrist or arm with your left hand to keep the seatbelt under control. Keep your left leg bent and straighten your right leg, in order to expose his right hook.
Post your left elbow on the mat, grab his right hook with your right hand and remove it; at the same time use your left foot to push you up, forward and into him with in order to come to your knees while keeping him onto his left side. He shouldn't be able to follow you because his right hook is missing and you are pinning his left arm on the mat with your armpit and weight.
Your opponent will try to restore his right hook, don't let him do it: quickly take a backstep with your right leg and push into him. At the same time turn your head and body to the left. You should end up being on all-fours while he is on a side back ride: his left hook deep, his right hook shallow or off, holding arm deep and pinned, choking arm shallow with flared elbow pointing upwards. If necessary, remove again his right hook with your right arm.
While your left arm is still controlling the seatbelt, grab his choking arm with your right arm and push it over your head while shrugging. Once free, pin him down with your left shoulder and move to your left; finish the escape by sliding your left elbow all the way to his right side. You should end up in his guard.
Basically, your left side is holding an pinning him while your right side is freeing you.
Your left armpit is taking care of the holding arm, so you just have to make sure the choking arm doesn't cause trouble: that is your left arm's job. You can use your left elbow for posting, if needed: even if the choking arm slips under your chin, it is going to take a while for the holding arm to slip and secure the choke because your left shoulder is pinning him down.
Your left arm will be exposed until the end of the escape. Keep an eye on it.
Your left leg is for getting on all-fours and keep you stable. It is important to stay on all-fours throughout the escape, as gravity is helping you by making him slide off your back and at the same time denying the choking arm a nice angle to attack.
Your right arm and leg are working together to remove his right hook and keep it off: this is your first checkpoint. When your base is stable and the hook is off, both arms will take care of the seatbelt; if you need extra force, stand on both feet and use gravity.
Your whole body movement along the 3D-axes should be to the left, back and down. Down is to pin him, left is to rotate and back is to weaken the control of his hooks and seatbelt.