In episode 12, Norm divides height to deck (65") by 9 levels so that each step is under 8". Later when finished, I count 8 levels. Did I miss-count or would perhaps the 9 levels have caused too short of a horizontal dimension per step?
Count risers, not treads.
Casey is correct, there is always one less tread than riser as you step up to the first tread then step up again to the landing.
Most building codes have a formula for indoor and outdoor stairs with maximum and minimums for risers and treads, along with a slight allowable variance in those numbers.