It is a movie called 'The Invaders' and you purchase the app for U.S. $0.99 [iTunes link] and then play it all you want. For a minute I thought it might be the sixties TV series with Roy Thinnes, but no such luck.
In fact, 'The Invaders' is a 1912 public domain silent western about Indians attacking an Army fort. You buy the app, download the 150 MB file to your iPhone or iPod touch, and watch the movie. Then I guess you throw it away, because it is not material that stands up to repeat viewings.
The developers have a bunch of other public domain titles in their Cinema Classics series, like 'Night of The Living Dead', but you can download or view most of these titles for free from the web anytime you want. You can also access them from the Internet Archive and watch them on your iPhone or iPod touch with Safari. At last count Night of The Living Dead was available on DVD from 23 firms, and you could view it for free on Google Video or YouTube. It's one of those films that inadvertently slipped into the public domain, leaving the creators with a lot of remorse and no money.
The same firm, LOL Software has dozens of iPhone apps, many that just collect news feeds from other sources and put them into an iPhone framework. LOL indeed. Yawn.