The Cosby Show was the American Idol of its time. In the mid-’80s it crushed everything scheduled against it and catapulted NBC from a distant third — as in last — in the Nielsen rankings to a dominant first for most of the rest of the 20th century.

Don’t look for it on DVD. There has been no release.

Roseanne tied The Cosby Show as most popular series of the 1989-90 season and was in Nielsen’s Top 5 for the first six seasons of its nine-year run. It, too, remains a DVD non-starter.

JAG, now in its 10th season on CBS, is not on disc either. But you can get My Big Fat Greek Life, which came and went in fewer than two months on the same network.

Harsh Realm hung around for one season on Fox. It was a distant last in its time period. It is on DVD. So too is Wonderfalls, which managed to survive only a month last year before Fox pulled the plug.

DVD sales of TV series have become a multibillion-dollar business. According to industry publications, total sales were about $2 billion in 2004, up from $1.5 billion the previous year. Nevertheless, it would seem there is no rhyme or reason as to what does and doesn’t hit the video store shelves. Actually, there are numerous reasons, according to industry experts.

"This began as a small, small business just three or four years ago," said Marc Rashba, vice president of catalog marketing for Sony Pictures Home Entertainment. "We got a lot of calls from producers and fans." That input influenced the first series Sony targeted for DVD. "A lot of the early [releases] were ones that were sort of seminal favorites or classic favorites for us. But it has evolved over time. Now we have a little bit more of a process in place. We regularly conduct polls on TV fan sites and such."

Sometimes such polls have to be eyed warily. "We do a little more homework because there was a show with Chuck Connors from [1987-88] called Werewolf," Rashba said. "We kept getting hundreds of e-mails about it. But when we did our homework, we found out it was three guys in North Carolina."

Quantum leap

Despite the high stakes, decisions on what to release on DVD remain an inexact science, he acknowledged. "We almost really don’t know. We kind of get to guess."

The traditional gauge of program popularity, the Nielsens, isn’t a reliable barometer of DVD demand. "We’ve learned ratings don’t necessarily translate to success on DVD at all," Rashba said. "Some of the surprises are shows we never thought really would click at all."

The No. 1 selling single release would fit into that category. Sales for the first season of Chappelle’s Show are approaching 2.5 million copies, more than the number of people who watched the Comedy Central series for free on a typical week. "When Paramount put it out," Rashba said, "they were totally caught short on that kind of phenomenon that just explodes on you. You can’t even fill the orders."

Another of the biggest sellers is a bigger shocker. Two editions of Family Guy, the animated Fox series, have sold about 3.5 million units. Only The Simpsons, which has sold almost five million sets of its first four seasons, tops those figures. "We know Family Guy took Fox by surprise," Rashba said. "They knew it was going to be successful. They just didn’t know it was going to be that successful."

Its afterlife has become such a sensation that Fox resuscitated it from cancellation, where it was jettisoned because the network couldn’t find an audience for it despite using every promotional gimmick and high-powered lead-in, including the Super Bowl, at its disposal.

Freaks and geeks

When it comes to DVDs, it seems to be preferable to have a small but rabid core of followers, rather than broad appeal that may be a mile wide but an inch deep.

"That’s why Fox is releasing something like Wonderfalls," said Gord Lacey, who has made a business of his self-created Web site tvshowsondvd.com, whose features include an alphabetical roster of shows on DVD. "Four episodes aired, but it’s coming out on DVD [along with episodes that didn’t air] because there are fans who will buy it."

Buffy the Vampire Slayer never approached the ratings of NYPD Blue. However, according to Lacey, "You’re going to sell more sets of Buffy because it’s got an active fan base."

Moderately rated shows whose primary appeal is to younger viewers tend to do better in their afterlife than Nielsen smashes, whose audience tends to be closer to Social Security than to puberty. This helps to explain why there has been no release of JAG. "That’s one I get asked about all the time," Lacey said.

Even when there is a perceived market, other hassles can keep a show from the DVD marketplace. "Sometimes it’s the willingness of the studio," Lacey said. "Older shows are a little bit more difficult [to get released]. Right now everyone is concentrating on the new shows, because that’s what people want."

The size of a studio’s library is another factor. "Warner Bros. has such a huge catalog, there might be a good show that they would do all right with, but there’s 30 others shows that they would do better with," Lacey said. "They’re probably going to release those 30 before the other one."

Let’s make a deal

Petty bickering between studios can keep shows from being released, especially older ones in which the contracts had no language for 21st century technology. "A lot of original show agreements were silent on the issue," Sony’s Rashba said. "You had a very different model, so you’d have a studio co-production sometimes with a network, or you’d have two studios co-producing. One took international rights for syndication and one took domestic. But when you get into other formats — Internet, DVD — they were silent. So there has to be a business discussion a lot of times with the original people." Sometimes this means their heirs are doing the negotiating.

Hammering out these deals can become a headache. "They may not all get along at this point," said Gary Scott Thompson, creator of the NBC series Las Vegas. "That’s a problem." This is a pitfall his show will not endure. Thompson began preparing for a DVD release from day one. Midway through the series’ second season on the air, season one is already on the market.

Seinfeld is a textbook example of the challenges of getting several constituencies on the same page. "`Monumental’ would be a great description because it was aligning a lot of different parties," Rashba said. "First and foremost is the talent. Then it is a Castle Rock-produced show in partnership with Shapiro/West. So we needed those three parties together before [Sony] even got involved. You had a lot of people with a lot of opinions. So it took a long time to get the whole plan together."

A major concern, according to Thompson, was the fear that releasing Seinfeld on DVD would harm the syndication ratings. Why would people who had every episode at their disposal bother to watch reruns with commercials? "It turns out the exact opposite was true," Thompson said.

This is becoming the common experience, said Rashba, who cites Friends as well as Seinfeld. "The syndication [ratings] of both these shows actually increased a little bit with the marketing around the DVDs."

Thompson feels the DVD release of Las Vegas, which features some racy outtakes, has given his series an enormous boost. "It was a great marketing tool for the second season. We’re up against Monday Night Football. There are a lot of guys who don’t watch our show, but I knew they would go and buy the DVD and possibly get hooked."

Behind the music

Obtaining the rights to soundtrack music, a process that ranges from time-consuming to impossible, also can pose an impenetrable roadblock. This is what kept Miami Vice out of the marketplace until just last month. For fans, it was worth the wait, since all the original music was cleared.

Then there’s another iconic ’80s series, Moonlighting. "The original studio that owned it didn’t want to put it out because of the rights issues for the music," said DVD Group president David Naylor, who is working on the show’s DVD release. "So Lions Gate decided to take a roll of the dice and is going to put it out complete with all the original music."

The difficulty of obtaining music rights has kept most vintage variety shows off the DVD shelves, according to Paul Brownstein, who is known in the business as "The Raider of the Lost Archives" because he specializes in producing discs of classic series. "The cost of the musical compositions — not the performers, just the songs they sing — can add up to more than we’d ever see in a royalty from DVD sales. You would be at a loss position on every single DVD that comes out."

One solution, a problematic one, is to replace the original soundtrack. "I’ve done three seasons of Felicity and all the original music was pulled out and replaced with a new score," said Naylor, whose company also has produced season sets for Alias and The X-Files.

Such machinations eventually will go the way of the 8-track and the Edsel. "The good news is, for a lot of the newer shows going forward [such as Las Vegas], everyone is sort of thinking about the DVD format," Rashba said. "We’re clearing shows for both the TV use as well as for DVDs."

Once and again

Talent doesn’t have the leverage that music composers do. "Every deal is different. Older shows fall under a lot of older contracts," Rashba said. "Residuals are probably not as substantial as something that is a hot show currently on a network." Some veteran stars have tried to recoup what they feel should be theirs by making outrageous demands to participate in the "extras." This, too, can delay a release.

Ultimately, however, if there is a market, a way will be found to serve it even if it takes awhile, Thompson said. "Don’t forget the audience really dictates what’s going on here. They’re the ones telling us what they want to see."

It has been that way from the start.