There are a lot of DS and 3DS models floating around on the market—the DS, DS Lite, DSi, DSi XL, 3DS and 3DS XL—and apparently some people find this confusing. Enough so that Nintendo released the above video detailing the exact differences between the DSi, 3DS and 3DS XL.
We don't remember this much fuss over the launch of, say, the Game Boy Advance. But maybe our rosy glasses are preventing us from seeing the truth: that Nintendo may want to reconsider its naming schemes (or possibly just release less hardware iterations).
Perhaps Nintendo is surprised over the number of DSi consoles that are still being sold? We don't have those numbers, unfortunately, but Black Friday may have been a wake-up call. Who knows? Either way, there's got to be at least this much confusion over the Wii and Wii U. Think there's a video for that coming soon as well?