You are really close on this. I've seen this tutorial from him countless times on youtube. The biggest issue on this is the spacing of the hooves once they have planted and start going from front to back. The front ones start slowing down after planting and the back ones vice-versa, meaning you would get a skating effect if you popped this in a scene somewhere. The spacing on the hooves for each frame have to be even or else it will skate, and not just that, the motion is off and kind of odd too as if the horse just stepped in some mud and is having a bit off a time trying to get out of it.
Still looks great, I love it!