A video data model that supports spatio-temporal querying in videos is presented. The data model is focused on the semantic content of video streams. Objects, events, activities, and spatial properties of objects are main interests of the model. The data model enables the user to query fuzzy spatio-temporal relationships between video objects and also trajectories of moving objects. A prototype of the proposed model has been implemented. (C) 2003 Elsevier Inc. All rights reserved.