Where do you think Amazon got it from? Their young typists didn't know the word, so they checked the Chakoteya site. And Darby's line reading is throwing you off. She says the word very quickly and doesn't articulate it. And she didn't need to, because buttinsky was in common use in the 1960s among working class Americans. Nobody misheard it at the time. If someone can find it, I'm confident the script will say buttinsky. Unless I'm wrong, of course.