Oh, how I wish the clip was a just a little bit longer. That's a stepping pace, as far as I can tell. He's definitely not trotting - it's a broken step, not 2 beat. Pacing is really obvious with both legs moving in the same direction on the same side, like someone paddling a canoe - not pacing. He's not fox trotting and he is not doing a true rack, which is more diagonal/squared up. But he is almost doing a rack, the difference being he is still too lateral in his movements, which is how you get the stepping pace. Squaring him up, by regulating his footfalls, working some poles, or in sand/deeper footing, if possible, will help you help him square up. Stepping pace isn't as undesirable as pacing, but it is not an ideal gait to allow a horse to keep *ventroflexion, additional joint strain, etc.* I didn't read ahead, so I don't know if I'm saying the same thing as someone else says in later posts to this question. Hope this helps in some way!