Weird. Funny. It looked planned, except that this guy looked genuinely stumped and baffled.
Maybe they had just planned to do this (spinning beachball show) in case it happened to one of their speakers.
Update: Aha, thanks to Ken for this article about the prank.
By the by, I read once that in OSX the spinning beachball does not mean "unexpected delay" as much as "this will take a moment, but you can now do tasks in other apps while it's going on". I am not sure if that's just a spin, but I do think that back in OS9, you couldn't do anything at all while a spinning cursor was showing.
By the by 2, have you noticed that interface elements tend to be abstracted into god's blue beyond when they are copied or remade? Tivo has a derivative of the spinning beachball where the coloring is so subtle that you have to look closely to notice that the thing is spinning at all.
And in early Mac OS versions, like OS 6, the active window had clean black striping symbolising a grip surface to show that here is where you grabbed if you wanted to move the window. In OS 8 and 9, these got grey tones and became less visible. In early OSX, they were transformed so they looked more like faint pin-striping. And now they are just gone. (In fact I have always thought that in OSX the visual difference between an active window and other windows is just way too subtle. It's just a shade darker grey is all.)