yes, they see the downloader's IP addresse, the same addresses seen when you download a game from your console using the official eShop, downloading the same exact files.
their server is a "cdn" (content delivery network), it's there to serve content that user ask. it's just doing that, whatever the IP or the device connecting to it.
if they didn't want anything else than a WiiU to download from their servers, they would use SSL and specific certificates only the console knows.
It's still possible to download by extracting the SSL certificate from the console, but that's just to show that the default cdn is not protected and they don't care which device access it.
what's protected on the other part, is the eshop content (image, game description, etc.), it uses a certificate to secure the access of the eShop data (and not the downloaded content) and to generate a ticket based on your console's ID.
