CBS News video: The peak of flu season in the United States is nearing. Already there is widespread activity in many states. Doctors are concerned because Australia just experienced its worst flu season in five years, and this could be representative of the flu season for the U.S. still to come. Some scientists have hypothesized that the mere 10% effectiveness of the flu vaccine is due to a mutating H3N2 flu strain. Click here to watch the full video.