Ducks are prey animals so its a natural instinct for them to not want to be around you since they don't move that great on land. When you see the videos of the ducks following people around everywhere, its usually because they were raised as a single duck since they are social animals and expect to grow up around other ducklings.
None of our ducks will come up to us. The chickens will walk up and aren't scared at all. In fact, our 2 year old is routinely seen putting a chicken into the wagon and taking them for a ride.
The more you are around them, the better they will get, although ours have never become true domesticated pets like a cat or something like that. We have a new batch of ducklings and they don't run at all from us. They let us hold them and pick them up, and most of our past ducklings that we have raised were the same way. as they get a little older though they start wanting their independence and get a little more skittish.
I know others have better luck, but for us during the past 3 years its been our experience with about 25 of them. For what its worth we have a mix of Mallards and Pekins and various other mixed breeds. We interact with them at least twice a day.