In the film releasing world, "window" is a term describing the amount of time between when a movie is released in theatres and when it comes out in ancillary markets. For example, The Social Network had about a six month window before it came out on DVD and Blu-Ray, and maybe another 2 months before it was streaming for free on Netflix.
The Social Network was, of course, a huge hit and usually the studios will keep that window big on hits, to maximize their profits. As long as you keep buying tickets, they're going to keep it in the theatres.
Which brings us to this
press release article on Newsmax.
A blockbuster documentary film that broke box-office records and exposed President Obama’s past is set for release as a DVD on the eve of the presidential elections.At this writing 2016 is #29 on the national box office charts, but it's only been out for 13 weeks. It's made $33 million dollars (I'm not sure which records have been broken; it's neither documentaries nor political documentaries) but it's safe to say that the people behind the movie are convinced that they're out of juice at the box office. Perhaps they're counting the $300 million dollars they'll make on video? Maybe they'll make another movie depicting the flood of viewers coming to see the first one, and call it an "re-enactment".
“2016: Obama’s America” rose quickly in ticket sales to become one the most successful documentaries ever released to theaters, will now have a major second act on Oct 16.
That’s when 2016 will be released as a DVD.