I donot see any gait issues. I do see a couple of things that would have me hesitate on the jumping schedule you are considering.
He is very light in bone and appears a bit tied in behind the knee. If he was 15.3 hands (or less), I would not be as concerned.. but he is huge at 16.3-17HH and it will really put stress on those legs. The other thing I notice is he is a bit over at the knee. This is actually NOT a fault in a horse that is going to jump.. (it is not THAT bad). He also has very small feet for his size. He looks like a TB/WB cross who inheritied the WB size and the TB legs. Especially the front legs.
His shoulder is very nice and he will be scopey over fences.. but the lands are going to do the damage. He has a nice roomy hock as well that I like.
In the riding videos he is very stiff (not surprising being relatively untrained and coming off stall rest). I think quieter hands, a bit more rein and a little more upright body position might help his head tossing and stiffness.
There is something about the outside of a horse that is good for the inside of a man. ~Winston Churchill
) Dinosaur Horse Trainer