It depends on the cycle for some. Mine one doesn't do a prewash for the 45mins QUICK cycle. But the ECO cycle does follow the normal prewash-then-wash process as described in the video. Hence I normally use the ECO cycle and put the correct amount of powder in both components. However in a hurry I sometimes just use the QUICK cycle and only use the main component as I know there is no point in adding more. The manual explained all this.