The video includes footage of an American who the video claims joined al-Qaeda and whom al-Zawahri refers to as "Azzam the American." The FBI has identified him as a 28-year-old Californian who converted to Islam, Adam Yehiye Gadahn.
He is wanted for questioning by the FBI for his role in terrorist activities.
Al-Zawahri and Gadahn do not appear together in the video.
(AP, Reuters, AFP)