Hey, don't forget, back then, commercials used to be good. Besides, it didn't last too awfully long, as I understand it, parental groups demanded that the shows stop doing their own commercials, because apparently it was "evil" for the characters to be selling products to kids.
Take a look at some others...
HOGAN'S HEROES Jell-O Commercial:
THE MUNSTERS Cheerios Commercial:
THE ALVIN SHOW Jell-O Commercial:
I know there was also a GREEN ACRES commercial where Oliver and Lisa met with Carol Channing (apparently she popped up in a lot of those commercials) to promote an orange juice brand, but I can't seem to find it anymore.