I don’t see a categorical difference between the interactivity of video games and the interactivity of more traditional mediums like television/radio. On a long continuum of interactivity we could certainly place video games on a side of “direct-highly-interactive” and something like radio on the polar opposite; but we <i>do</i> interact with these apparent one directional outputs. It’s just less direct.
With a video game, we expect to have near complete control (within the confines of the system) where our inputs are immediately correlated to some reaction on the screen. With TV, our interaction is a little less direct. Instead of an immediate reaction to pressing a button, there’s a lag time between, but reaction nonetheless. Those television programs that induce observers to change the channel (or simply turn the TV/radio off) are subsequently pushed off the air. Or, modified in some way to cater to a more appropriate target audience. In other words, if stupid people watch the show, the jokes/dialogue will get more stupid. If a show has an extremely large audience, they often feel the pressure to take on more social/political/topical issues; consider themes of “The Simpsons”, “Family Guy”, “South Park”, in their later seasons compared to the earlier seasons. The size and type of audience has a direct (or more indirect) impact of what the show’s themes will be. And, has anyone ever called into a radio show? Whether you get through or not, you’ve essentially pressed the ‘A’ button. I don’t see why we should discriminate on “interactivity” being instantaneous and predictable vs variable and subtle.
Perhaps somewhere closer to the middle of the continuum would be a DVD menu; or better yet the “spectate” function of many competitive video games. The spectate function within League of Legends or Starcraft 2 give the spectator the ability to see the game played from a different perspective, and to modify the perspective in real time. The spectator may not impact the result of a match, but their unique exercise of skill and judgment in deciding what is important to consider (graphs of army strength, economic factors, which character to follow and when etc..) if expressed (recorded…?) would certainly be the subject of intellectual property. There are professional spectators, well paid for their expertise in this role!