Over 45 with a very good memory?

I remember watching a short horror film in the late 70s / early 80s.
It was part of a series of short films - about 1 hour long. In the
film a guy found a package hidden inside his wall and it turned into a
devil like character eventually in a nightmarish type way. I remember
it appearing on a rocking chair in the film and laughing in a horror
film type way. I want to know what it was.

Why do I want to know? I've had a (mild) phobia of empty chairs ever
since seeing this film and want to find it and watch it again out of
curiosity.

Long shot - but what the hell.