Please quote the portion of the article that states they claimed the attack was due to the video, because I am not seeing it upon first read. Thanks.
That was not the point of that article. The article was to establish that this group acts violently to defend their radical brand of Islam.
Ansar al Sharia claimed it was in response to the video when they claimed responsibility for the attack. When they later retracted they still showed sympathy and support for defending the honor of the prophet.
Is this gonna be one of those cases where you cherry pick and ignore the pieces of info that don't fit your preconceived narrative? Of course, the answer is always yes.