What made the box office debuts of both "Obsession" and "Backrooms" so surprising is how well they fared against major studio releases.

Backrooms shattered A24's record. Obsession beat Star Wars. Two Sleepy People sold to mk2. Three films from YouTube creators just remade the box office.

The building success of Obsession speaks to the power of strong reviews and stronger word of mouth – and twentysomething YouTube film-makers