I have kept snakes for years and know what I am talking about. Cribos live in South America, eat monkeys, and are NOT poisonous or constrictors. They just grab, overpower and swallow their prey alive, often back first since that is usually the part they grab first. I doubt you would see a video of a monkey being swallowed alive because of all of the protests and indignation it would create. Some anthropologists suspect that mankind feared (and worshpped) dragons so much because they were a composite of their three greatest predators when much smaller and more vulnerable - Snakes, birds and felines.