fact, discussion of no-plane theories has been banned from certain conspiracy theory websites and advocates have sometimes been threatened with violence by posters at other conspiracy theory websites. Cover-up allegations Cockpit recorders According to the 9/11 Commission Report, both black boxes from Flight 77 and both black boxes from Flight 93 were recovered. Flight 77's CVR was said to be too damaged to yield any data. On April 18, 2002, the FBI allowed the families of victims from Flight 93 to listen to the voice recordings. In April 2006, a transcript of the CVR was released as part of the Zacarias Moussaoui trial. Two men, Michael Bellone and Nicholas DeMasi, who worked extensively in the wreckage of the World Trade Center, said in the book Behind-The-Scenes: Ground Zero that they helped federal agents find three of the four "black boxes" from the jetliners: Bin Laden tapes A series of interviews, audio and videotapes were released in the years following the 9/11 attacks that were reported to be from Osama bin Laden. In the first of these the speaker denied responsibility for the attacks. On September 17, 2001, in a statement issued to Al Jazeera, Bin Laden is quoted as saying: "The U.S. government has consistently blamed me for being behind every occasion its enemies attack it. I would like to assure the world that I did not plan the recent attacks, which seems to have been planned by people for personal reasons." In a tape released in December 2001 known as 'the Jalalabad tape', the speaker is alleged to have foreknowledge of the attacks. The Central Intelligence Agency claimed the tape was probably from Osama bin Laden. Some observers, especially people in the Muslim world, doubted the authenticity of the tape. On December 20, 2001, German TV channel "Das Erste" broadcast an analysis of the White House's translation of the videotape. On the program Monitor, two independent translators and an expert on Oriental Studies found the White House's translation to be both inaccurate and manipulative, stating, "At the most important places where it is held to prove the guilt of bin Laden, it is not identical with the Arabic", and that the words used that indicate foreknowledge can not be heard at all in the original. Prof. Gernot Rotter, professor of Islamic and Arabic Studies at the Asia-Africa Institute at the University of Hamburg, said "The American translators who listened