linksunten.indymedia is a widely known platform of the German Antifa. During the most recent weeks many texts glorifying or whitewashing the Hamburg G20 riots were published there. Texts can be submitted by any anonymous person, however the website owners decide whether they leave it online or not – so there is reason to see responsibility under law.
I wouldn't be surprised either if it becomes accessible again just after the German federal elections in 4 weeks.