Dolphins are animals who mean no harm and just want food, like the rest of us. So, it should come as no surprise at all that a dolphin would go after the food in the hand of what, in the most recent case, was a little girl. You don’t dangle food before a dolphin.
In my video, a woman discovered that lesson the hard way. After basically toying with the creature, keeping food from it, giving it some, then keeping it from it, the dolphin had enough and shooed her away.