YouTube's most watched video of 2017? A man singing as an oyster

It's YouTube's roundup of the top trending videos of the year, and in 2017 a non-US video hit No. 1 on the chart.

The honour goes to a clip from a Thai singing competition, showing a man dressed in a full-body oyster suit crooning and rapping a song with a title that loosely translates to ‘Love you until the world turns into dust.’

YouTube's trending ranking is based on a combination of views, shares, comments, likes and other criteria. As the world's largest video site, YouTube's most popular items provide a peek at what captivated the world over the course of the year.

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 three 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.

Despacito, of course, was the blowout winner for pure view count, at 4.46 billion, to become the most viewed video ever. Because music videos are uniformly the most viewed clips on YouTube every year, the company provides a separate ranking of top music videos for the year.

Also in the most viral ranking are two clips linked to singer-songwriter Ed Sheeran, including a dance choreography video and his appearance on a Carpool Karaoke segment on The Late Late Show.

Together, the top 10 trending videos have more than 633 million views, 83 million more than last year's list, and were watched for over 40 million hours.