The hit ITV period drama, penned by Oscar-winning writer Lord Julian Fellowes, follows the lives of the aristocratic Crawley family and their servants.
But in the YouTube video, they've been manipulated into speaking the words of One Direction's debut single What Makes You Beautiful.
The track took the number one spot in 2011 and has since sold more than 5m copies worldwide.
Whatever would the acerbic Dowager Countess of Grantham say?
"Well, now I've seen it all," Maggie Smith's popular character is heard to declare.