HELSINKI, Finland (AP) -- A 15-year-old schoolboy was fined Friday for posting a video on YouTube showing a karaoke performance of his teacher and for claiming she was a lunatic.

In the first case of its kind in Finland, Nurmes District Court found Toni Vesikko guilty of intentional defamation and fined him 90 euros, or about $120. He also was ordered to pay 800 euros ($1,000) in damages for "causing harm and suffering" and 2,200 euros ($3,000) in court costs.

Vesikko, who took the video of his teacher singing karaoke at a school party on April 30, admitted posting the video on the popular video-sharing site YouTube a day later. He said he did it as a prank and had not intended to insult the teacher.

But the court said Vesikko's actions "falsified facts" - about the institution and the teacher's mental state - and caused her to suffer anxiety, depression and insomnia. The video was watched more than 600 times before Vesikko took it off Google Inc.'s YouTube on May 7 on the orders of the principal of the school, near Lieksa, 330 miles from Helsinki.

The video, which Vesikko called in English "Karaoke of the mental hospital," named the teacher and said she was "a lunatic singing at the karaoke of the mental hospital."

The Nurmes court found that the video had become "very well known and public" after its release, both in school and regionally, and could be accessed internationally. It said the video added anguish for the teacher, who had already been teased by pupils for about two years, according to her own account.