We just shot two steers that we fed all summer. Hit them right in the head between eyes and ears, the magic cross. The steers hit the ground with their heads in the grain bucket. DEAD. Now, we slit the juglar to have them bleed out. There were muscle spasms and nerve twitches until they bled out, basically until the heart was empty, about 2 minutes. Yes, it looks as if the animal, inclduing horses killed with captive bolts are alive, but they are dead, stone cold dead, the front of the brain is basically blow apart, there is nothing there to feel pain. If you look at the eyes of an animal that has been shot in the head, by the time it hits the ground the eye is blue and the cornea/pupil has no reaction. DEAD. There is no pain, there is no anything, the brain has ceased to function when it gets shot in the head, the muscle spasms and nerves are reacting to the death also.
I have assisted in many many deaths of animals at the clinic, big and small ones. With an injection, the animal is overdosed and the heart stops beating and the animal is dead. Sometimes the animal will fight the injection and make noise or move around, but they are still in a "coma like state". Beuthanisia Special is a high dose of barbituate, it puts their heart to sleep immediately.
A shot in the head kills the brain immediately, but the body, especially in a big animal has to die, but the brain is gone already. Yes, some go wrong, but some vet assisted ones go wrong also.
To make it easier to understand, when a person is considered brain dead, but kept on a respirato for organ transplants, they will breath but have no feeling or anything, the brain has ceased to function,but the nerves and such move until the heart is finished. Captive bolts are the same thing, the brain is dead immediately and the body quits when the heart does.
These videos are done to keep the "humaniacs and bleeding hearts feeling sorry for the horses and to keep the fight alive. Like somebody else said, we slaughter horses, but process all the other living creatures.