The invention concerns a method and system for identifying commercial message segments of a video signal. A set of rules is applied for determining the occurrence of commercial messages with a higher degree of accuracy as compared to conventional methods. In general, method includes the steps of monitoring a digital bit stream comprising the video signal, detecting a change in a control field of the digital bit stream, and then selectively generating a commercial event notification responsive to the detecting step. According to one aspect of the invention, a change in at least one of a video sequence header and a sequence display extension can be detected. Alternatively, or in addition to checking for a change in control field, the method can comprise the step of detecting a change in an informational parameter of the video signal exclusive of the audio-visual content.