On the outside chance anyone somehow missed the obvious, the press release announcing “Along for the Bride” — a half-hour TLC reality show premiering Thanksgiving night — makes the source connection explicit: “Think ‘Bridesmaids’ the movie turning into a TV show.”

It’s hardly a secret that unscripted TV has long used movies as models for series concepts. Lately, though, reality show producers, perhaps driven by the burgeoning challenge of gaining attention, have become more brazen.

Investigation Discovery has been particularly adept at crafting true-crime concepts that immediately evoke popular movies, such as in “Dark Minds,” in which an imprisoned serial killer helps dissect cold cases (a la “The Silence of the Lambs”), and “Deadly Sins,” whose main vice would be the sloth in its thematic resemblance to the thriller “Seven.”

Such exercises are becoming fairly common across the Discovery family. Take TLC’s “Secret Princes” — a U.K. format about international royals looking for brides in the U.S., seemingly plucked from the rib of the comedy “Coming to America.” Even “Extreme Cougar Wives” — a new special featuring young men and much older women — sounds a bit like the cult classic “Harold & Maude,” though that’s probably giving the network too much credit.

For its part, Lifetime forged an equally overt link with “My Life Is a Lifetime Movie,” a reality show that had the advantage of replicating the women-in-peril stories we’ve come to know and mock at a fraction of the cost — and in half the time to watch.

Not that male-oriented fare is any better. The premiere of TNT’s “The Great Escape” managed a movie-mirroring twofer, with the same title as the 1963 war epic and the same basic idea as “Escape From Alcatraz.” Then again, much of Discovery’s popular manly-men-try-to-get-rich-quick fare plays like a bad knockoff of “The Treasure of the Sierra Madre.”

Presumably, these shows are distinct enough to prevent armies of lawyers from descending on them; still, when networks begin using direct references to movies in publicity efforts, they appear to be skirting pretty near opening a can of legal whoop-ass.

Why hew so closely to movie plots? Because doing so creates a kind of shorthand, helping the audience grasp the material almost instantly, and process it — consciously or not — in the context of something they might have already seen or that at least sounds familiar.

That’s helpful, since in many instances viewers don’t actively seek these programs out but simply stumble upon them. Viewed that way, the practice is clever, if a trifle oily — capitalizing on the renewable supply of amateur exhibitionists to replicate movies on the cheap.

The blurring between movies and unscripted TV isn’t strictly conceptual, by the way, but can also be seen in the more cinematic production values and ever-more-elaborate dramatic reenactments within so-called reality and even what passes for documentaries.

As a case in point check out the Smithsonian Channel’s “Enemies Within: Joe McCarthy,” which premieres Sunday. What initially looks like another straightforward historical examination of the red-baiting 1950s demagogue periodically detours, rather jarringly, into scripted scenes featuring actors playing McCarthy and others. As clumsily assembled, it’s as if the made-for-TV movie “Tail Gunner Joe” had an illegitimate baby with an actual documentary.

Reality TV is hardly the only entertainment form guilty of being derivative — including, of course, promiscuously eating and regurgitating its own. Still, some of these movie-inspired programs have become so blatant as to foster a creeping sense of creative stagnation.

In a comprehensive analysis published several years ago, WGA West assistant exec director Charles Slocum dissected the roots of reality TV. “Reality-based programs marry low-cost production techniques from news with narrative storylines from drama and comedy,” he wrote. Such programming, he added, “has one appeal, which it shares with fiction — we as viewers hope, desperately, to find something relevant to our own lives.”

By that measure, the surprise isn’t reality TV taking another page from writers’ scripts but looking to the bigscreen for inspiration. For those who grew up in darkened theaters, it’s also why unscripted TV often feels like deja vu all over again.