YouTube mania ultimately turned PSY’s Gangnam Style into a bona-fide chart hit in the US, based on sales. In 2013, though, viral videos will have an even more direct impact on Billboard’s Hot 100 singles chart.

The industry magazine announced yesterday that from this week, YouTube streams will be factored into the Hot 100, alongside physical and digital sales, radio airplay and on-demand streaming.

The first beneficiary? Harlem Shake, of course. Baauer’s soundtrack to helmet-clad meme-buffoonery is sitting proudly atop this week’s Hot 100 chart thanks in large part to 103m streams of the song in the last seven days.

That said, it’s also selling well in the US: indie label Mad Decent sold 262k downloads of the track this week too.

Billboard’s algorithm update is based on data from Nielsen tracking official videos on YouTube (including Vevo) as well as “user-generated clips that utilise authorised audio” through the ContentID system – something Mad Decent has been on top of from early in Harlem Shake’s viral rise.

“The notion that a song has to sell in order to be a hit feels a little two or three years ago to me,” Billboard’s Bill Werde tells the New York Times.

“The music business today — much to its credit — has started to learn that there are lots of different ways a song can be a hit, and lots of different ways that the business can benefit from it being a hit.”

Good news for YouTube, and a new factor for labels to consider when planning their video campaigns. Meanwhile, this also feels like an appropriate moment to remind you about Harlem Shake Roulette. Oh, also this: