I somehow find this far less ridiculous than say, people holding a convention about videogames or anime. At least being fat is -literally- inseparable from these people's lives.
I don't know why this angers you. It just makes me kind of sad. Yes, it's amusing, but I still want the people in this video to be happy and live long long lives free of obesity related illnesses. Yes, statistically unlikely but... I mean, why should they hate themselves? So you can feel superior?