The article below keeps talking about "YK" - what they really mean is VK, vKontakte. Here's a link to the original blogpost by the author, Jamie Barlett:
Country’s YK social media platform has five times the unique users of Facebook, some say due to access to pirated moviesFacebook may be the world’s largest social media platform with more than a billion unique users. But in Russia the website touts just 20% of the unique users afforded the country’s preferred social media platform, YK, with a reported 50 million users.
The reason: YK apparently turns a blind eye to pirated movies, while coveting online dating — both major draws to the targeted youth demo. YK’s catalog of pirated movies (especially new releases) is immense, according to Jamie Bartlett, director of the center for the analysis of social media at the think tank Demos.