For the first three weeks of the new year, the enhanced edition of Chris Kyle’s memoir, American Sniper, led Apple’s iBooks bestseller list, consistently landing several spots above the title’s standard e-book. Its hot streak was a rare victory for enhanced e-books (especially over their unenhanced counterparts). On the whole, sales of enhanced e-books have fallen short of expectations since publishers began investing in the format, which incorporates video and other interactive features, roughly five years ago.

Is American Sniper’s place at the top of Apple’s chart a one-off occurrence, owing to the popularity of the film adaptation (which raked in six Oscar nominations), or is it a harbinger of good things to come for enhanced e-books—pointing to a new trend, enhancing titles with TV and film adaptations, that may help publishers sell what has been a historically difficult format to market?

The enhanced e-book for American Sniper was released simultaneously with the hardcover in 2012, well before the film premiered on Jan. 16, 2015, and the supplemental material is not directly related to the movie. It contains 12 original interviews with Kyle interspersed between chapters, in which the NAVY Seal (who died in 2013) touches on the book’s themes—and it also includes a video with his wife, Taya Kyle.

“Instantly after publication [in 2012], American Sniper became a huge bestseller and the enhanced e-book sales were part of that frenzy, becoming the bestselling enhanced e-book of the time,” said Sharyn Rosenblum, v-p, senior director of media relations at HarperCollins. “With the explosion of book sales now that the movie is out and has become a blockbuster, it makes perfect sense that the e-book would be equally in demand again.” And it is—according to HarperCollins CEO Brian Murray, the enhanced e-book has now sold more than 166,000 copies.

Other publishers are also successfully experimenting with incorporating movie tie-in content into enhanced e-books. “These days, an MTI enhanced e-book is always on the table for us with big-screen and small-screen adaptations,” said Beth deGuzman, v-p, digital and paperback publisher at Grand Central. The imprint has released two movie tie-in enhanced e-books of novels by romance writer Nicholas Sparks that have been adapted into feature films.

The first Sparks book to be developed into an enhanced MTI e-book was Safe Haven, released in December 2012, alongside the print movie tie-in edition. “We were all so thrilled with the sales, which were in several multiples of what enhanced e-books typically sell,” said deGuzman. The second enhanced MTI title was The Best of Me, released Jan. 20, 2015. “The original intention was to publish the enhanced e-book simultaneously with the print MTI editions, but this was a case of the production deadline being too early for the movie studio,” noted deGuzman. “So we did the next best thing: we changed the on-sale date of the enhanced e-book to tie into the DVD/BluRay release of the movie.” Grand Central will also be issuing an enhanced e-book for Sparks’s The Choice—the film started shooting last fall.

According to deGuzman, the enhanced movie tie-ins are a win for everyone involved. “The more marketing and exposure, the better the chances of success for the adaptations,” she said. “The bigger the success of these adaptations, the more likely we are to sell more copies of the underlying book. That’s a recipe for happiness for all parties—authors, agents, publishers, studios.”

Grand Central does rely, per deGuzman, on the movie studio’s recognition that movie tie-in editions serve as crucial marketing tools for the movie. “I cannot stress enough how appreciative we are that the movie studios spend time and effort and resources to provide us with [additional material],” noted deGuzman. The enhanced editions of Sparks’s novels include content from the studios, such as interviews with the actors in each film and behind-the-scenes footage.

Penguin Random House has seen a “great response” to its transformation of coffee table companion books for film and TV into enhanced e-books, including Geoffrey C. Ward and Ken Burns’s The Roosevelts, and J.W. Rinzler’s The Making of Star Wars series, according to Nina von Moltke, senior v-p, director of digital publishing development. “Movie tie-ins do represent a great opportunity, as they enable us to leverage the marketing of the studio, providing additional promotional opportunities for what are often backlist titles,” noted von Moltke. “But we always keep a reader’s interest in mind and are careful not to turn a book into a marketing vehicle for a movie. What seems to work best in the market are editions that provide unique and relevant content.”

Publishers developing enhanced e-books also cite retailer participation as a major factor in marketing a title successfully. “We have produced enhanced e-books since retailers started to support additional media and features in their e-book reader platforms,” said von Moltke. “Not every retail platform supports the same feature sets, but we work with all of them very closely to optimize... functionality for the respective e-book reading systems.” The publisher added that most retail platforms support additional audio and video content at the outset, but PRH has since experimented with “adding other functionality that enhances the reading experience itself.”

“From a corporate strategy point of view, we continue to experiment with product in conjunction with our authors and where the technology and the content can marry up nicely to offer a richer consumer experience,” said Harper’s Rosenblum. “We believe that there is value in adding features for fans, we need retailers to support visibility and exposure to these products. The current example of Sniper proves that when a retailer like Apple gives it exposure and appropriate promotion the product sells really well. So EEBs can be huge when the right product comes along.”