The Anne Frank House, the museum which was the hiding place for Anne Frank, her family, the Van Pels family and Fritz Pfeffer during World War 2, has uploaded the only known film footage of Anne onto Youtube. The film was taken on July 22, 1941, and shows a newly-wed couple walking out of the building (No. 37 Merwedeplein, Amsterdam) adjacent to the home Anne was living in at the time (No. 39 Merwedeplein). (This was about one year prior to the Frank family going into hiding.) Anne, who was 13-years-old at the time, appears at the nine-second mark of the video, and can be seen leaning out of the window to take a look at the couple.
The Anne Frank Channel on Youtube can be subscribed to here.