What breed of duck is it? Muscovy? It doesn't look like it's in the air cell yet, but the first pic is rather confusing. Does it have a misshapen air cell (common with shipped eggs)? Also the fact you don't hear peeping means it isn't in the air cell yet. It's a good sign you still see movement, though. It looks close to internally pipping.
We arn't sure what breed they are but the air pocket has changed it looks as though it has been popped. We are very frightful we have already lost 2 and don't want to loose this one. In the third picture the duck egg shows a dark spot and we are not sure if its a pip. He is still moving but we fear if we don't help him or help him to soon he won't make it. He might be a mallard but are not positive all our duck eggs were diffrent breeds.
My ducks take 26 - 28 days to hatch. It looks to me that part of the duck is into the air sac. If tre veins dry up it will suffocate. Make a safe hole, thumb tack size in the air sac part of the egg.
If the dark spot IS where it's trying to pip (which does sometimes happen), then it is upside down in there and may need help getting out. Have you read through this link: