Okay I didn't listen to it cause I can't listen to the sound right now but that most likely isn't in the UK as its illegal for any animal to be killed in front of another animal and most animals are stunned out of the sight of the other animals. The way the vessels in a sheep are means that slitting the animals throat is the most effective way of killing the animal and for the most part they are dead instantly. Having seen many animals been PTS I can tell you that often animals will still move after death just due to the nervous system shutting down, so don't let that put you off, anything that dies evn naturally can twitch after death.
Animals in this country are raised in some of the best conditions in the world and for the most part sheep have an amazing life just chilling in fields all day.They will have their diet specially set out for them, perfect grass, worming, vaccines etc. If people didn't eat animals then we wouldn't keep them. People would have no use for cows, sheep, chickens etc and they would become endangered/extinct like all the other animals that we have no use for or take up land that we need for crops.
I justify eating meat through having free range or locally sourced meat. I know that these animals have had good lives and having in some cases even helped raise these animals on placement I know that they couldn't have had better lives. If you buy UK meat (which has a red tractor) for the most part you can guarantee the animals have optimum welfare.
Though i do admit that some things in the industry do need improving, but this will happen over time, especially when you compare the farming industry now to what it was 20-30 years ago. Also you have to admit that agriculture in general harms wildlife and other animals whether its from crop growth or for meat. No industry is perfect and improvement is needed overall.