coming from a TV background, i'll throw in my two cents (as if i'm an expert and as if i know what im talking about).
a well written and well produced/edited commercial can produce a :30, :20, :15 and :10 second versions. i see these all the time. its basically the same video with certain parts added or removed. it also depends on timing, maybe the stations only wanted a few :20's and the grandma was edited out of the approved :20 spot. or Denny's left it up to the stations on which versions they wanted to air and had several different :20 or :30 seconds spots. there's probably a number of things that went into the grandma not making it to air.
i have seen a few of these Denny's spots air, but i have never seen (or remember) the grandma, but i have satellite and rarely watch local TV.
