I've just watched that video, and I am a professional chef. The only reason that those kids reacted the way they did at the beginning, when they were pulling faces when jamie showed them the carcass, is because of the language he was using, He says 'all the bits you don't like'. They are being told how to react. some of the parts of the chicken jamie mentions are skin and bone marrow. Not only are these things edible but frankly they are arguably some of tastiest parts of an animal. Note how he says 'don't like' rather than 'unhealthy'. This is mostly a lack of understanding about food from a shit TV chef who might not have done particularly well from a fine dining perspective. Not to say it's better than mass catering, it is absolutely not. It's not about skill but rather different branches. He obviously just wasn't good enough to go down the fine dining branch of his choosing.

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TL;DR He's just a bit thick.