"The ban was imposed after prosecutors told the court that clips insulting former Turkish leader Mustafa Kemal Ataturk had appeared on the site. According to Turkish media, there has been a "virtual war" between Greek and Turkish users of the site, with both sides posting insulting videos."
Apparently dissing the founding-father of modern-day Turkey can result in a prison sentence. That sure was one self-important asshole!
http://news.bbc.co.uk/2/hi/europe/6427355.stm