It is certainly a very strong driver for the child to want to do what the adult does, be it household work, shopping, cleaning the car.. they see and they want to copy especially when the desire and belief in oneself of 'me do it!' is so strong. With this activity they needed no encouragement either, the bucket of water was probably enough though!
Practical Life Activities are activities where the child is being exposed to basic every day activities that are both purposeful and meaningful that they can do using 'real' materials, in turn building confidence and a greater sense of contributing to the family unit. This particular example of a practical life activity would come under 'care of person'. It's an activity that they 'can do' when provided with the opportunity, needs little direction and for the children today kept them concentrating on their work for a solid amount of time. Concentration in particular and providing opportunities to deepen this is of utmost importance. Interruptions, verbal or otherwise are kept to a minimum.
We are consciously encouraging and fostering independence from a early age where appropriate, it's not always possible when time is not on our side, but the ideal is in the forefront of our minds!