A processor of an apparatus plays a video on a display device and receives a command one or more times. In response to receiving the command, the processor performs object detection in a hierarchical manner with respect to objects in the video. The processor displays a video image from the video. Upon receiving the command for a first time, the processor detects in the video image a first set of one or more objects at a first hierarchical level and highlights the first set of one or more objects. Upon receiving the command for a second time, the processor detects in the video image a second set of one or more objects at a second hierarchical level below the first hierarchical level and highlights the second set of one or more objects.