Umm... I don't know the precise answer. But I think it's approximately "dumber than dirt," but not quite "dumber than shit." Are you sure this person isn't in management somewhere?

BWAHAHAHAHAHHAHAHAHAHA. That's priceless.

Oh, come on now -- maybe this client is going through chemo, too. I had a supervisor at my 'spare' job who used to constantly harp on me about my (ahem) casual posting of payments (we had a really stupid kind of handbuilt primitive software system that wouldn't let you go back and change an entry if you inadvertently hit 'cash' instead of 'check') and I'd get so caught up in BS-ing with the clients that I would mix 'em up on occasion -- so when my hair all fell out, I'd whip off my wig and say "Duuuude, see all those empty hair follicles? WTF do you think has been holding in my brains all these years? They're all leaking out! Cut a sick chile some slack already!"
On the other hand, maybe the guy truly IS just a moron -- you DID say entertainment industry, didn't you? We have a new deal in my hospital where they are having RN's doing charting directly into the computer with the idea of (eventual) paperless charts (snort) ... some of the older gals have little to no outside PC experience and it's been quite eye-opening to troubleshoot various hardware issues for them -- actually, the powercord question could've come from any of them! And my IT(ahem again) team has been outsourced to Ross Perot, and they're not much better! Sad.

Wow. That's scary. Really freakin' scary.

So, we are to conclude from this person's complete and utter lack of knowledge of all electrically functioning stuff that they grew up Amish, right? I mean, even a toaster has a power cord that - strangely enough - looks a lot like EVERY OTHER FREAKIN' POWER CORD!

Ok, I'm better now.

I only over-reacted because I'm dealing with my own idiots.

Deep breath.