Bondage and restriction is a fine art of pushing a submissive to their physical limits, making them stretch, suffer, and contort in ways they never thought they could tolerate. They want to do it to please their master, to prove they can do it, and because they crave the feeling of being restrained. It makes their minds go away, as they subsume all their thoughts into the feelings as they cut off from the world.
This particular bottom is going through almost a ritualistic restraint and cutoff from the world. She gets pushed more and more as she gets more restricted, and those restrictions become extreme. She is bound in rope first, and then shoved into the stocks to take things to more intense levels. Then the leg spreaders and chains go in place, and at each step you can watch her go away more and more. She gets pushed to her bondage extremes, overwhelming her with sensations especially as the rope ends up run against her pussy. You can see her mind shut down like a true bondage slut, though the last step is when the blinders and gags go on her, and she just goes away.