Power planers aren't the best for large flat surfaces, they're designed predominantly for planing anything narrower than the planer itself. On a large surface they gouge material out and they generally make a large mess of the work even if all you're wanting to do is scrub material off as fast as you can. Lou's video shows you how to make a power planer far more accurate and better suited for the task of scrubbing by a few little alterations such as grinding the corners of the knives, which makes a massive difference.