I don't know if they still do them but the three major TV networks used to preview each new season with a promo film about the newly-debuting programs. I worked briefly on the one for ABC's 1983 Fall Season and no one ever gave me a satisfactory answer to where these promo films were shown.
This is the one for ABC's 1969 season. You won't remember most of these shows but you may spot some people who later appeared on shows you do remember…