To look at these questions, I reviewed the types of pouring at the following apparatus: Concrete tube forming apparatus. I built this apparatus using concrete forming tubes and a long cardboard tube. Though it is narrow, it is stable because the whole thing is taped together with three supporting cross pieces taped to the table itself.
The child below found the clear plastic tube embedded between two of the concrete forms. It is hard to see what both his hands were doing, but he did seem to be using a fine touch to control the speed of his pour with greater precision and accuracy.
The child pictured below found the highest level to pour into. She was on her tip toes and reaching as high as she could. And unlike the child pictured above, she could not see where she was pouring.