Something in the Basement, is a 1986 short horror film directed and written by Victor Salva which also was his first film.
A youth, played by Nathan Forrest Winters, is waiting for his brother to return home from a bloody war. However he encounters an ancient evil creature in the basement of his house claiming his older brother died.
The short played at film festivals, where it was met with acclaim. Famous director Francis Ford Coppola saw it and decided to produce Salva's aforementioned Clownhouse. Since then, the film has more or less vanished, with very few mentions of it on the internet. Its whereabouts are currently unknown.
It is likely that Winters (or his family) have kept it from circulating after the director of the film Victor Salva sexually molested Winters on the set of the film Clownhouse (as they did with the incredibly scarce 2003 DVD release of Clownhouse, of which only a few copies were ever made).