Wow, that is one scarey video. I would march to my house, get the gun and shoot that horse right then and there. Nice to hear that the lady in the video said the same thing.
But, to the OP, I think you have years of undoing to do and laying down was just too much to ask in this particular situation. As has been pointed out, you did make some progress. Baby steps working towards the lying down. Unless you saw some behavior to indicate otherwise, I'll bet it'll happen within the next few sessions.
He probably has no idea what is expected of him; he's like a pubescent teen that's never heard of school enrolled in kindergarten class.
I think you won pretty good with the stall issue. Regardless of what/who was around it, you got him in there without blindfolding again. Someone suggested keeping a journal. I think that's a great idea. A bad day might really frustrate you if you can't go back and look at what you started with and the little gains on the good days.
Good luck and keep us posted! :)