From the New York Times:
The Anne Frank Museum in Amsterdam, which preserves the memory of the young diarist who died of typhus in the Bergen-Belsen concentration camp in 1945, posted the only known film footage of Anne Frank on a new YouTube channel launched last week. According to the museum, the film was shot on July 22, 1941, to record the wedding of a woman who lived next door to the Franks. About nine seconds in to the silent film embedded above, the camera tilts up from the bride and groom to show young Anne leaning out of the window of her house to see them.
In the five days since the channel was launched, the video has already been viewed more than 1.6 million times.