The featurette

Years ago, in order to draw interest to an upcoming film, a featurette would be produced. It was not a trailer but a little story about the feature.

This is the best of the offerings...

Alfred Hitchcock's Psycho.

Alfred Hitchcock’s "The Birds"...a fine analysis

And these are more like "behind the scenes" or the "making of" featurettes...

 

A Dream Comes True

[Filming of Shakespeare's A Midsummer Night's Dream]

1936

The Train

John Frankenheimer

1964

Prince of Terror

1972