Helping babies out of the egg usually ends badly. Unfortunately it's sometimes necessary if the hatching isn't progressing and the duckling is in obvious distress. On yours, that's the egg sac with the accompanying umbilical which would have attached it to the egg. As outpost said, "egg wrapping" will help. Wrap it up in a very slightly damp wash cloth or towel and let it finish developing. You'll know how long because he'll try to "hatch" out of the washcloth when he's ready. If he wiggles out and is still a bit weak, give him a drink of water and put him back. A dab of antibiotic ointment on that red spot wouldn't hurt either.
Handling eggs too much during the last stage before hatching can cause the babies to move out of position and can cause the temperature to vary too much causing poor hatching. Best bet is, when they are very close to hatching, hands off. It's very hard to do, but really is best. Watch for pipping, watch for them to unzip the shell... but unless it's an emergency you really do just have to trust that they will hatch.
Best of luck!
