This year, the most viral clip stems from "The Mask Singer," a celebrity singing competition where the performers wear elaborate masks and costumes to conceal their identities. The concept originated in Korea but has spread to Thailand, Vietnam and China. Clips from the competition were viewed over 3 billion times in total in 2017. The Oyster Mask video from Thailand was the most popular, the first time a Thai video has been the No. 1 viral video on YouTube.