In Kurt Vonnegut, Jr's "Harrison Bergeron," the media, like everything, is meant to promote and ensure equality. There are a couple of instances where the reader can see the media in action.
The first example of the role of media is in the decription of George Bergeron. He wears a tiny radio reciever in his ear that emits harsh noises to interrupt his thoughts every few seconds. These noises are meant to keep intelligent people, like George, "from taking unfair advantage of their brains." By constantly keeping people with the ability to think from thinking, the government-run media, in effect, keeps people from questioning whether the government is doing things right or that are really good for the people.
The second glimpse at the media is the broadcast of the ballet that is interrupted by a news bulletin. This broadcast gives the reader a clearer vision of what this government's version of "equality" really is and the result of it. For one thing, we see that because of the government-issued handicaps, no one is able to excel at anything. None of the dancers can reach their real potential because they are weighted down by government-issued sacks of bird shot. The announcer "like all announcers, had a serious speech impediment," and has difficulty even speaking, much less giving the news in a clear manner. The person in control of the video is so incompetant that s/he puts the picture of Harrison "upside down, then sideways, then upside down again, then right side up" on the screen.
All these examples of the "equality" that has been mandated that are broadcast over the television show the devistating effects of that supposed equality--mediocrity is the highest to which anyone can aspire, and even mediocrity is probably unattainable when too many restraints are put on people.
Finally, the media is meant to inform the government of any straying from the laws. Diana Moon Glampers, despite the incompetence of the newspeople, knows exactly where to find Harrison and silence him. This is probably the most frightening aspect of how the goverment uses the media to control the people.
For more information about the story "Harrison Bergeron" see the links below. The first link seems to directly address your question with this discussion of television:
In "Harrison Bergeron", Vonnegut uses some of the ideas Minow discussed, particularly when he portrays television as a desensitizing, numbing, and definitely a thought-stifling—rather than thought provoking—medium. When Harrison goes to the television station instead of to the Legislature to start his revolution, Vonnegut illustrates that awesome power Minow describes in his speech. Vonnegut seems to say that Harrison's power to reach the people and make a new reality (declaring himself emperor) stems from controlling television. Clearly, the government, or at least the Handicapper General, also understands that power.
I hope this answer is helpful.