How did Neville break free of the Full-Body Bind curse (Petrificus Totalus) without using the counter-curse?

Question

I'm the biggest fan of the Full-Body Bind and I was shocked to see what happened after the last use of the curse in Deathly Hallows (chapter 36).

Harry pulled the Invisibility Cloak from inside his robes, swung it over himself, and sprang to his feet, as Neville moved too.
In one swift, fluid motion, Neville broke free of the Body-Bind Curse upon him;

How did Neville do this? I could maybe believe that he used the counter-curse non-verbally, but the "swift, fluid motion" part suggests that he did it by brute force, despite the rest of the series putting me under the impression that this was impossible. For example, if it were possible, I certainly would've expected Harry to break free of it near the end of Half-Blood Prince, or for any of the bigger Death Eaters to be able to break free when they were hit by it in any of the last three books. I wasn't even aware that attempting to move while under this curse was possible.

Answer 1

If I recall correctly, this is because, having sacrificed himself in the forest, Harry had bestowed the rebels with the same protection that Lily's sacrifice had bestowed upon himself. This meant Voldemort's spells could no longer affect them, and in the case of Neville, who was already under one of his spells, the spell was weakened enough that Neville was able to break free of it.

Harry explains this to Voldemort later on in the chapter (page 591):

"You won't be killing anyone else tonight, said Harry as they circled, and stared into each other's eyes, green into red. "You won't be able to kill any of them, ever again. Don't you get it? I was ready to die to stop you hurting these people--"

"But you did not!"

"--I meant to, and that's what did it. I've done what my mother did. They're protected from you. Haven't you noticed how none of the spells you put on them are binding? You can't torture them. You can't touch them. You don't learn from your mistakes, Riddle, do you?"

So this was just an edge case related to Harry's love-sacrifice, and not anything to do with the curse itself.