A database of video clips is provided wherein each video clip depicts normal or abnormal behavioral patterns in children aged from birth and older or in adults. The behavior patterns in the video clip database are relevant to neurodevelopmental disorders. The behavior patterns depicted in the video clips are indexed and searchable. Also provided is a method of assessing a behavioral abnormality in the test subject. The normal and abnormal patterns for a given behavior can be compared to a test subject performing the same behavior depicted in the video library, to permit a medical professional to assess the extent of a behavioral abnormality in the test subject.