And now, back by unpopular demand...

TV on DVD has become one of the most popular and lucrative corners of the home-entertainment world. Recent series such as "Six Feet Under" as well as classics like "Mission: Impossible" thrill fans and plump up corporate bottom lines. The hot new releases and the old favorites make perfect sense -- the viewership is ready and waiting, credit cards in hand.

So how do you explain the recent release of "Blue Thunder," a barely remembered 1984 drama about a police helicopter team that costarred a young Dana Carvey? It was well before his "SNL" heyday and lasted just 11 episodes. Or "Good Morning, World," a long-forgotten 1967-68 series about a morning-radio team? And how about the 1983- 84 sitcom "Buffalo Bill," about an unlikable TV talk-show host?

But wait, there's more: "The Best of Hootenanny" just came out, featuring musical performances from a long-unseen 1963- 64 ABC series that capitalized on the folk-music revival of the day and which was canceled after the Beatles exploded on the scene. Coming in February is season one of "Anything But Love," a romantic comedy that -- despite stars Jamie Lee Curtis and Richard Lewis -- struggled to make a lasting impact on ABC from 1989-1992.

"Who asked for these?" you might wonder, but then again, the person asking for them might have been you.

"Every cancel ed TV series had millions of people who watched it and presumably millions who remember it," said Billy Ingram, founder of TVParty.com, a TV history website -- its links to Amazon.com help sell TV DVDs -- that gets two and a half million page-hits a month. "If 20 to 25 percent of the nation watched a series, that just wasn't enough at the time. And it wasn't enough if a series was critically acclaimed but didn't get good ratings."

There's even a term for it , "Brilliant but Cancelled" -- coined by a series on the discontinued pop-culture Trio cable network. Ingram singles out as an example the three-disc release of the complete "Buffalo Bill," a critically praised series starring the grumpy character actor Dabney Coleman.

Approximately 18.2 percent of the DVD market in 2006 was for TV shows, up from 17 percent in 2005, according to Nielsen VideoScan. While the majority of that is for current and recent hit shows, as well as undisputed classics, there is an audience educated by both the Internet and cable channels like TV Land about the careers of television "auteurs" -- the producers, writers , and actors who moved from show to show.

Two factors seem to be at work. As the children -- and adults -- of the 1950s and early '60s learn to use 21st-century entertainment technology, they realize that classic television shows they haven't seen or thought about for 40 to 50 years can be resurrected on DVD.

That explains recent releases by various companies of such programs as "Perry Mason," "Cheyenne," "Sgt. Bilko," "Mr. Peepers," Edward R. Murrow's "Person to Person," and "The Jack Paar Collection," which includes Paar as host of "The Tonight Show" and "The Jack Paar Show."

"They've gotten the DVD," says Paul Brownstein, an independent executive producer of TV-show DVDs who supervised last year's "Bilko" and a series of "Gun-smoke" multi-disc sets, of the 50-something and older fans of these shows. "They may not know how to download movies on the Internet yet or program their iPods, but the DVD is reaching this audience."

The rationale behind some of the newer releases is different. It's based on the realization that a TV ratings "failure" defined by the mass culture of the 1960s-1980s, when three networks ruled, looks much different in our fragmented times. It also acknowledges that some of those "failures" were good shows that deserve -- even at this late date -- to be discovered.

Garson Foos, co-head of Shout! Factory, says older or more obscure titles can sell about 10,000 copies, which can be profitable if expenses are controlled. (By comparison, the hip Comedy Central series "Chappelle's Show" quickly sold more than 2 million units when its first season was released in 2004.)

The greatest expense can be music licensing -- one reason why the three-disc " Best of Hootenanny" sells for a higher-than-normal $44.95. But the upcoming two-disc "Johnny Carson Show" retails for just $24.98 because Foos's company only had to negotiate with Carson's ex-wife, Joanne, who had the copies. CBS had not maintained ownership.

Foos hopes it sells beyond the 10,000 mark. "The show is really good and really funny," he said. "But is the Carson fan base so deep it will be into this, or is it just about the ['Tonight'] show?"

Arny Schorr, whose S'More Entertainment has released "Good Morning, World," was attracted to it because it was the first show by executive producers Carl Reiner and Sheldon Leonard after their landmark "The Dick Van Dyke Show." It is also the program that "Laugh-In" producer George Schlatter watched to discover a very young Goldie Hawn, who played the neighbor of one of the main characters.

"Everything I put out has some kind of pedigree -- some kind of cachet," Schorr said. "It's a little bit below the radar, but it's amazing the number of people who remember them."

Sometimes lost footage has to be assembled from miscellaneous sources and the search can become a curatorial mission, too. In putting together last year's three-disc "Sgt. Bilko" set devoted to the 1955-1959 service comedy, Brownstein discovered a previously unseen "audition tape" for the show at the University of Wisconsin, where producer Nat Hiken's archives are housed. He looked at it and discovered it was a veritable "pilot." He included it as an extra. "It's like an art historian looking for something else to put up in a museum," he said. "I'm in the legacy business."

Variety and talk programs of the 1950s seemed especially of the moment , and often were broadcast live. Thus, they've been largely forgotten until recently. Fortunately, kinescope copies of varying quality were made by pointing a camera at a television set. But finding them can be hard because networks didn't always see much reason to save them.

Such programs now are being recognized as historic, which is fueling their re release. For instance, both "The Jack Paar Collection" and "Edward R. Murrow: The Best of Person to Person" include interviews with Robert Kennedy . Paar's is from early 1964, Kennedy's first after the 1963 assassination of his brother . Murrow's, amazingly, is from 1957, when Kennedy was chief counsel of the Senate Select Committee on Labor Management and the latest member of his family, in Murrow's words, to seek public service.

For the actors and personalities who starred in these long-unseen shows, the renewed interest from DVD releases can be very satisfying. For instance, 79-year-old Clint Walker, who was the quietly authoritative star of the first hourlong TV western, ABC's 1955-1963 series "Cheyenne," now finds himself busy autographing copies.

"I'm still amazed at all the fans I still have," Walker said, from his Northern California home. "I think a lot of my fans want to go back to those shows. I know I get a lot of letters from people who say, 'Now I want my grandchildren to see the heroes I had.' It's very rewarding, very flattering."

Portions of this story first appeared in the Denver Post.