Facebook is working on a video app for set-top boxes, according to a Wednesday report. The social network wants to deliver longer-form video content — and with it video ads — to the living room TV, the one screen it has been unable to reach. The Facebook app soon could be available on a variety of set-top boxes, including Apple TV. The initiative reportedly began in earnest last summer, after incubating for years as a concept. News of this effort follows Facebook’s recent announcement that it was refining its News Feed to favor longer-form videos, which can include mid-roll ad breaks.