Grammar books tell us that the word media should be treated as a plural. You're supposed to say, "The media are covering the story," not "The media is covering the story." Nobody can explain what "a medium" is in this context, and the media people themselves often do not follow this rule, or they follow it inconsistently. I've read articles and even books where in one paragraph it's plural, in the next it's singular, and in the next it's plural again. It's beginning to take on the qualities of a noun like sheep, which can be either singular or plural.
The word is actually one of several Latin-derived plurals that have gradually become singular in English. Another example is data, which is a shibboleth among techies. You're supposed to say "The data are misleading" rather than "The data is misleading," and you'll get a stiff whacking if you get it wrong, even if hardly anyone uses the singular datum.
Of course, there are other examples that not even the pickiest of grammar cops treats as plural. You never hear anyone say "The agenda are ready," even though agenda is as much a Latin plural as media and data. Then there are Italian plurals like opera and spaghetti that English speakers have always treated as singular. If you heard someone say "The spaghetti are cooking," you'd give that person a stiff whacking!
But unlike any of those examples, the plurality of media is more than just a grammar issue. People almost always use the word to suggest that news coverage is distorted, slanted, or subtly manipulated. This connotation does not exist in terms such as "the newspapers" or "the networks." Although by now the plural use of media is mostly a formality, its transformation into a singular noun contributed to the popular image of the news business as a single unified entity conspiring to present the news in a particular way. All the critics left, right, and center talk about the media this way, even when they attach the term to a plural verb just to show what a smartypants they are.