Understanding them is what will make a site popular or not. Audience behavior is culture driven. Today's Web audience is the equivalent of the Rock'n Roll generation, except that this is not a community around music, but around virtual worlds and communities creating a new form of fantasy. Today's Web is page based, using a space based design in 2D rather than the time based design video, audio and animation bring to the screen. Now of course, it's not just a matter of playing video on a screen.
Content needs to reflect the transformation of technology and culture.