That does seem confusing, I admit. I certainly do not hold writers and video producers to different standards -- albeit that video producers have often held themselves to lower standards.
BUT ... Mr. Kuffs has made it clear he thought the glimpse to be something old and standard. It does have that kind of feel to it, which is a hard thing to pin one's finger on, and often an easy mistake to make. When I worked on Penn & Teller's "How To Play With Your Food," I almost made a similar faux pas with regard to the Blister Trick. At the last moment -- we were virtually in galley already -- I discovered the trick belonged to Jack Kent Tillar. Penn & Teller held the book up in order to contact Mr. Tillar and obtain permission. (Despite the fact that a columnist at the time took us to task for incomplete credits, the charge was woefully unjustified. I think we left out a credit for the Cross Cut Force!)
In this case, as Mr. Kuffs has pointed out, he provided other credits which indicate that his intentions to credit properly were sincere. And he has made it clear here that he made an error and is pleased to have the correction.
Regarding the video instructions I mentioned that tipped the Hilford glimpse, it's very clear if you watch the video that the producers are woefully unprepared, making it up as they go along, and when one of them happens to think of this glimpse on the spot, he simply tips it spontaneously on camera, says he's not sure who deserves credit, and never gives it a second thought. For $160 for for a wallet and an unwatchable accompanying video, the producers could have taken a bit of time and energy and either found the credit, or cut the uncredited mention. It's clear they simply did not care one way or the other.
So the context, in both cases, provides some evidence -- at least to me -- about the intentions of these various parties. It has nothing to do with applying different standards.