Al Jazeera said the recording was made months before the attack. US officials have identified Al Haznawi as one of four attackers on United Airlines Flight 93, which crashed in rural Pennsylvania.
Dr Gunaratna said that prior to the release of the video there was still some doubt in the minds of Muslims about whether al-Qaeda were definitely responsible for the US attacks.
But the broadcast finally erased that doubt provoking criticism from Muslims everywhere concerned that the extremist group was giving Islam a bad name, said Dr Gunaratna.
He said he believed that Western military leaders have privately accepted that the war in Afghanistan, where the Royal Marines are busy combing mountain lairs used by al-Qaeda fighters, was 'far from over'.
