If you refer to the following situation shown in video at 19:30. What are the recommended ways to release of back rope choke?
There are a number of problems with demonstration videos like this. First of all, the attacker is essentially frozen in place while the defender is able to move and do stuff. It's not realistic at all.
In general, when you watch "demonstration" videos, make a note whenever the student seems to freeze while the instructor goes right along through a series of complex movements. When you see that, realize it's basically just theory. And martial arts is full of theory. Most of it is bogus, because it wouldn't work against a struggling opponent.
Second, this particular choke shown in the video is not one you would likely see in real life. In other words, even with a rope, people don't choke like that.
More realistically, an attacker wanting to choke someone from behind with a rope will immediately cross the two ends of the rope behind the defender so that the choke is actually completed. Without that, it's not actually a choke. It must be cinched tight around the neck, not just placed around the front of the neck. And most people, even untrained people, instinctively know this.
But let's suppose this scenario is for real. If the attacker doesn't actually intend to cinch the rope and instead just places it around the front of the defender's neck from behind the defender, what happens if the attacker pulls back hard on the rope?
If he pulls back on the rope while there's a big gap between him and the defender, the defender will end up getting "clothes lined" (ie, thrown backwards to the ground).
That's not a choke, then. So the video demonstrates a situation that just wouldn't happen in real life. Common sense will tell you that.
So what should the attacker be doing in this situation if he's really trying to choke someone from behind?
The attacker must make sure there's no way for the defender to fall backwards when he begins to pull back on the rope. He has to move up super close behind the defender so that there's no gap between him and the defender. He should be able to kiss the back of the defender's head he's so close. With no room between attacker and defender, there's no room for the defender to fall backwards.
Next, the attacker's fists would actually be placed against the back of the defender's neck as he's holding the rope and choking. He will be trying to pull the rope tightly against the neck by bringing his fists closer together while holding the rope. That applies the choke. Crossing the rope behind the defender's neck is a more common variation of this choke.
While he's doing this, the attacker is going to stick his chest right up against the defender's back, without any gap between them. This will prevent the defender from being able to turn around to face the attacker (which would nullify the choke).
And for extra control over the defender, he might want to wrap one of his legs around the front of the defender while making sure to lower his hips down a bit (like the beginning of sitting down). This will make sure the defender can't throw him forwards and can't step away from the attacker or turn around. The attacker's other leg will be free for stability, because the defender will likely thrash around from side to side.
Okay, what I've just described is a more realistic scenario. The one in the video shows a completely non-committed, frozen attacker who has no real intent of choking the defender, as evidence by lack of pulling and too much distance between him and the defender. Whatever defense strategy follows from this bogus setup is itself bogus.
Without the proper choke setup, there are many things you as a defender can do. For example: 1) You can simply turn around to face the attacker. 2) You can drop your weight down while holding onto the rope and throw the attacker forward over your head or shoulder. 3) You can simply to look to the side, and the rope will no longer be at your trachea. From there, you can step around and grab the attacker's arms and perform some kind of a throw. 4) You can sit back onto the ground while holding the rope, then roll backwards onto your back, and then use your legs to press against his stomach and throw him forwards with your legs while pulling at the rope. 5) You can grab the rope with both hands, tuck your chin to your chest (pinning the rope at your trachea), and then turn around to face your attacker, ducking under the rope as you do this and then popping your head back up at the end. Doing so will release the hold. Etc. Etc.
You'll see a ton of neat and plausible ways out of this choke in all the different martial arts out there, but they generally do assume the attacker has no idea what he's doing. Assumptions like that are not helpful to you. You really ought to assume that the attacker knows what he's doing and design your defenses accordingly. If it works against someone who's trying their best and who knows what they're doing, then it should work on everyone else as well.
As for defenses against the proper setup for this choke, you need to put yourself in the position of the attacker and ask how the defender could cause problems for you.
For one thing, you're pulling back on his neck while sitting back into your stance a bit. What if he were to simply sit down a little, lowering his head slightly so that it's now under your chin. Then he'll be in a perfect position to launch his head back at your chin. He just has to push off the ground hard while arching his back backwards.
If you're the attacker, the warning sign that he's able to do this is him lowering down. If you see him do that, you should get your head out of the way and pull him back up with the rope.
Another thing the defender could do is to snake one of his legs back behind your leg, if you're the attacker. He does that by crossing his right leg behind his left leg first, and then he places it down behind your left leg (snaking it around). Now he can twist his shoulders clockwise, so that his right shoulder pushes against the right side of your chest. It will put pressure on you to move to the left. But since he has placed his right leg behind your left leg, when you get pushed to the left, you will be tripped - or you will be thrown - to the left.
Stomping on the feet is another thing that can be tried. It's not very reliable by itself, though. It's primarily used to distract the attacker. A distracted attacker might loosen up on his grip or might put some distance between him and you. It might also cause him to lose his balance while you're struggling with him.
Another thing you as the attacker must worry about is the fact that the defender has control of his arms still. It's possible the defender can reach back and press his fingers into your eyes or grab your ears or throat. He can also reach back to grab your testicles.
I don't consider those very reliable defense techniques, but like with stomping, they might distract the attacker long enough to do something else without him noticing.
With his arms free, the real worry for you as the attacker is if the defender snakes his right arm back between you and him and reaches around the back of your left hip. He can use his grip on your belt or pants to pull you off balance, causing you to step to the side and offering him a way to break free.
The defender may also be able to use one of his free hands to reach down and grab the leg that you might have wrapped around the front of one of his legs (you may have done that in order to add extra control over his movement). If he can pull up on your leg, he can push back against you, causing you to fall backwards to the ground.
Once on the ground, he can use the opportunity to get out of the choke much more easily. For example, he can roll backwards or back and to the side, slipping his head out of the choke.
There are many other defenses I've not mentioned. It's hard to go through them all here. I'm sure I wouldn't be able to come up with a complete list, either.
My main point here is that, in order for any defense to be worth anything, the attack envisioned must be as good as you can make it. Because in the real world, your attackers aren't going to be playing around. You don't have the luxury of assuming the attacker is going to make huge, basic mistakes.
One other thing. Be VERY careful with this in your practice. It's so easy to break a neck, collapse a wind pipe, break your wrist as you fall, etc. Both partners need to be sure to dial down the amount of force and go easy while still providing resistance. And communicate. Give each other feedback as to the effectiveness of both the attack and the defense. Be honest, but don't go crazy.
Hope that helps.