This is the kind of thing we do to bugs and small animals, but it feels so cruel when it's happening to us. Think about it. Haven't you taken a box or a bottle and put it over a cat or a bug respectively? We've all done it just to see what the animal will do. They hate it and they freak out. Imagine if you were on the beach like these people and then a giant put a bucket over you. The first thing you'd do is start to scream and punch the bucket.
I like how this woman's reaction is to shield the child, as if they were about to be crushed instead of trapped. If anything she's helping the kid get caught. She should be throwing the child out of the way so it can run and have a fighting chance.