Open up! Chimpanzee 'asks' zoo visitors to free him from enclosure with sign language in heartbreaking film

Tapping on the window the chimp, believed to be kept in a Welsh zoo, repeatedly urges people standing on the other side of the glass to let him outside. The chimp is seen in the video motioning to a watching visitor to unlock the bolt on what appears to be a glass door and lift the window, so he can be free.