Almost 10 years ago, I asked about this on a similiar site as this one.  No one ever replied to my question.   My hopes are not high now:

In the early to mid 70s, ABC always previewd their Saturday Morning Fall TV schedule the Friday Night PRIOR to the start of the season.   These previews were in the forms of specials usually featuring kid characters from ABC shows (Brady Bunch, Partridge Family, etc.)  There was the usual variety show stammering over unrehearsed lines seen for the first time on the cue cards in front of them, but they also featured clips from all the great new cartoons premiering tomorrow morning (!).   Themes were Funshine Saturday, Mission Magic, the Bradys Meet Saturday Morning, etc.)  Though these were broadcast only once, I imagine they were also used to court cereal, candy and toy advertisers along the ABC Network lines.

CBS did it once I remember.  I think I recall NBC doing it a few times.

Does anyone remember these?   Does anyone know where I can get my hands on some of these?