A method, apparatus, system, and signal-bearing medium that, in an embodiment, calculate scores for cells within a program based on a speed at which the cells were presented and a frequency that the cells were presented. A cell includes one or more frames of presentable data. Chapters within the program are then determined and located within the program based on gradients of the scores that exceed a threshold. The scores are calculated based on incrementing a score for each cell each time the cell is presented and by different amounts depending on the speed at which the cell is presented. In an embodiment, the score is incremented by a larger amount in response to a slower presentation speed of the associated cell. In an embodiment, scores may be received from multiple clients where the program was presented, the scores may be aggregated for all the clients, and the chapters may be determined based on the aggregated scores. The scores may further be used to change the presentation speed of the program based on the scores of the cells being presented or skipped.