I was watching Modern Family and saw the commercial! How cute was that?

Back in the day, this would be the exact NIGHTMARE "serious actors" would fear. Commercial work was considered the bottom of the heap. Now I see this a lot with say Tom Selleck and his reverse mortgage ads in the middle of Blue Bloods. It must be planned.

I agree, planned for maximum financial profits (lol)!

I worded my post incorrectly: Fred was in Modern Family and in The Princess Bride, but not in Princess Bride-inspired commercial that followed Modern Family. So, was the placement worth the cost? Do they also show this Culligan commercial during the new game show Fred hosts, something with kids?

It's really hard to say. Commercials are planned at the network level and local level (station or cable company -- they get slots for local businesses and revenue). The local ads can be sold for particular time slots (evening news, super bowl, etc), a time period (morning hours, prime time, after hours, etc.), or a package of so many runs at differing time slots. The sales department has slots to fill and those they don't fill with specific placement get filled by traffic -- specifically or random.

I don't know how much attention is paid to detail these days -- there used to be more things you couldn't advertise during prime time or what were considered children's viewing times or family times. With so many cable channels now and even Victoria's Secret programming -- things have changed, but I suspect that while there are fewer products and taboo times, the basics are still the same. And mistakes are made -- we've all seen commercials that run after an event is over. But when it happens more than once or twice, I would not seem to be coincidence.