Relative to saddle fit. The video and accompanying info leaves out several very important points. One, no horse is truly symmetrical. Two, no horse's back does not change shape while it is moving. With that in mind how can a rigid tree saddle properly fit any horse, IT CAN NOT. A properly fit saddle must allow for the unsymmetrical back and changing shapes of the horse's back as it moves. The only saddle capable of doing this is the flex panel saddles. Here's a good explanation: HILL VIEW FARMS
As to the signature gaits of the Paso, the Peruvian Paso, and the Racking horse. The rack, the corto, the largo, the fino, the paso llano, are all the same gait. Exactly the same foot fall. Any one that tells you differently has not viewed videos of these gaits and studied the foot fall. The signature gait of the TWH is the running walk(although some TWH prefer the rack). The running walk is at the exact opposite end of the "pacing spectrum", ie, in the running walk the rear foot leaves the ground before the front foot on the same side, and is also a 4 beat gait, but with differing foot fall from the rack.