Are you sure about cast commercials existing? The Fourth Season of TBH corresponds to the sixth season of The Andy Griffith Show (1965-1966). On the DVD set for season 6 of TAGS, there are no cast commercials. Perhaps CBS ceased doing them at that time. When they went to color, I think that there was a much greater expenses so it may have been that instead of having one or two sponsors, that's when the networks started having anyone with the money pay for a commercial. On the other hand, it may be cutting out cast commercials (if they do exist) would be a way for CBS to cut costs.