Netflix is a popular subscription streaming video service available in the U.S., as well as Canada, Mexico, South America, the Caribbean, United Kingdom, Ireland, Sweden, Denmark, Norway, Finland, and the Netherlands. For a monthly fee, it provides all-you-can-watch movies and TV series. Exact content varies by region, but is catalog in nature, not first run. Think of it as re-runs on demand.
Netflix has an app for the iPhone, iPod touch, and iPad, and is built-in to the Apple TV. It can also be watched via the web browser on the Mac.