A colleague has announced that media as a plural is the hill he is willing to die on.
Though I am dubious about most sticklers who stake out the usages they will grasp tightly to the death, I sympathize; media as a plural is very much my own preference. Newspapers are a medium. Magazines are a medium. Television is a medium. Film is a medium. Collectively they are media. I dislike "the media is" constructions because the singular gives credence to the mistaken, and partisan, notion that the media are monolithic.
But it has fallen to my lot to live and work in the twenty-first century, not the nineteenth, and media has been following the path trod by data. Datum seldom crops up except in scientific or technical writing . Data has become both a count noun—the data from multiple studies have made clear that global warming is occurring—and a mass noun—the data from research on global warming is overwhelming.
And now media, as Bryan Garner points out in Garner's Modern English Usage (fourth edition): "Media, as a shortened form of communications media is increasingly used as a mass noun ... especially in a collocation such as social media. ... While that usage still makes some squeamish, it must be accepted as standard."
Media as a singular violates the grammar of Latin, from which it is taken, but it is English now, and Latin, though it has influenced English profoundly, does not determine it. English is made by us, its users in speech and writing, and we have made media a singular.