Trying to find a specific video

[Kilroy]

Hey everyone, I was wondering if anyone could help with a bit of an issue I'm having.
I'm looking for a specific video (or more specifically, part of a video) to show a friend.

The episode had a story where one of the theorists working on a big project was invited to see the construction and planning of said thing that was being built. The theorist ended up sort of pointing to a random part of the diagram and asked something about if it was alright or if that design would work, and it turned out that the engineers making it had made a mistake, and he'd accidentally found it.

As you can see, my memory of it beyond broad strokes is kind of awful.
Any help would be greatly appreciated.

[J!!]

The story you're thinking of is about Richard Feynman. Who, as I recall, was touring some kind of nuclear facility under construction, but not really understanding much of what the engineers were telling him. Trying to seem engaged, Feynman pointed to some random component of a blueprint and asked "what happens if this fails?". The chief engineer looked​ at it, thought for a moment, and realized that such a failure would result in the destruction of the entire facility. By dumb luck he'd stumbled upon a design flaw. But to the engineers, it seemed that he had taken a quick glance at their plans and instantly spotted a mistake that their entire team had been missing for months, saving them from possible catastrophe. This cemented Feynman's reputation as a legendary super-genius.

I have no idea what video Chuck tells that story in, but since it involves Richard Feynman, your best bet is probably The Day After, or something else that involves nuclear weapons.