Dr. James McSharry, Professor Emeritus at Albany Medical College, gives an overview of influenza viruses in this short lecture from the American Society for Microbiology. Flu viruses can affect a wide variety of animals, and at the start of the talk you can get a look at how flu viruses were detected in patterns that matched the routes of bird migrations.
The structure of flu viruses is also presented, and you can hear an explanation of how viruses strains are named - why they get associated letters and numbers (the letter is based on the properties of the viral antigens). McSharry talks about human flu viruses as well, especially starting at the sixth minute.
In the last part of the presentation, after a brief overview of viral replication, myriad therapeutics for flu viruses are discussed. While we have experimental compounds and flu vaccines, we still have not conquered the flu; McSharry takes the time to mention some problems in flu vaccines, which must be redeveloped each year. There could be some progress in that area; researchers are striving to develop a vaccine targeting a region of the flu virus common to all influenza viruses.