I just watched your video. Her feet, especially that one, are far worse than Scout's were after his frostbite. His at least maintained normal coloration and although they are curled they aren't curled completely under. I'm assuming that she has naturally slate colored legs and feet, whereas Scout's were yellow, so it's hard to say if she's that badly discolored or if she had naturally dark feet to start with.
This is a tough call. She looks alert and aware of what's going on around her, and she's certainly still interested in eating. I almost culled Scout one night early into his problem, but decided to sleep on it before making a final decision. The next morning I caught him up on top of Mama Heating Pad, looking adorable (even though the little stinker couldn't figure out how to get back down) so I didn't cull. I figured if he wasn't ready to give up then neither was I. Now he's out in the coop and run with the girls and although his feet are still deformed, he gets around fine and roosts well. He can still outrun me, but then I'm old so it's not much of a challenge.
Whatever you decide to do, you can do it knowing that you are doing what you think is best for her.
You might try rubbing some castor oil into her feet and legs. Sounds silly, but it really did help Scout tremendously - it relieved his pain almost immediately and increased circulation to the damaged parts. Once his pain was relieved, he wasn't favoring the feet as much and didn't pull them up when he walked, which helped with his flexibility. Couldn't hurt, and knowing I was doing something to at least relieve his pain helped on the rough days!!
I don't know if you've been to Scout's page yet, but at the very bottom there is a video of him out in the yard with the girls, and you can see that his curled feet don't seem to impact him at all. I'm praying that it works out that way for your girl, too. The only thing I question is whether antibiotics at this stage of the damage will help that much, but I'll leave advice on that to people far more knowledgeable than I am. I wish you and your lady all the best, and I'm following this closely.