1. A visual attention detector for predicting a region in a video likely to attract visual attention, the visual attention detector comprising: a processing circuit configured to perform operations comprising: operation as a feature extraction unit configured to extract a spatiotemporal feature from a local region in a video, a spatiotemporal feature representing a spatial and a temporal change in an image in the local region; operation as a hashing unit configured to: convert a spatiotemporal feature value for the local region into a hash value using a hash function, and select a training value mapped to the hash value for the local region using a hash table wherein a training value learned in advance for a spatiotemporal feature is registered in a bucket mapped to a hash value; and operation as an attention measure determining unit configured to determine an attention measure for the local region based on a distance between the spatiotemporal feature value for the local region and the selected training value such that the larger the distance the larger the attention measure.