Here's a video that my husband took back when our ducks were 8 weeks old. He opened their house and then walked behind them, not herding them at all.
[VIDEO]
Most domestic duck breeds can't fly. If mine start off in the doorway of their house, then they get about six feet away or so, tops. And that's with them about 2 feet off the ground and they are flapping for all they are worth. It's more like a really long jump than flying. Mallards can fly and...