Methods for interactive selecting video queries consisting of training images from a video for a video similarity search and for displaying the results of the similarity search are disclosed. The user selects a time interval in the video as a query definition of training images for training an image class statistical model. Time intervals can be as short as one frame or consist of disjoint segments or shots. A statistical model of the image class defined by the training images is calculated on-the-fly from feature vectors extracted from transforms of the training images. For each frame in the video, a feature vector is extracted from the transform of the frame, and a similarity measure is calculated using the feature vector and the image class statistical model. The similarity measure is derived from the likelihood of a Gaussian model producing the frame. The similarity is then presented graphically, which allows the time structure of the video to be visualized and browsed. Similarity can be rapidly calculated for other video files as well, which enables content-based retrieval by example. A content-aware video browser featuring interactive similarity measurement is presented. A method for selecting training segments involves mouse click-and-drag operations over a time bar representing the duration of the video; similarity results are displayed as shades in the time bar. Another method involves selecting periodic frames of the video as endpoints for the training segment.