It's the UA portal. I go through mileageplusmall.com to get to buy.com, but the product with buy.com is backordered. They have it available through one of theirmerchants (altvideo.com maybe). It looks like you're buying it on the buy.com site with checkout through google checkout (for the 2 bonus miles per dollar). But the product is not shipping from buy. It's shipping from the third party merchant.
If all of this is hard to follow (which I'm sure it is), try to think of Amazon.com and Amazon marketplace. If you go to Amazon and you see the link x# available new and used and you click in that link for a better price than Amazon, you're still buying through Amazon but from a third party. It seems the same with buy.com although they don't have individual sellers (only businesses).
Hopefully that made more sense. It's very hard to put into words, especially if you have no upfront knowledge of the marketplace type setup.
Buy.com is getting 2x MP miles and the 2X Google checkout miles which is a great deal for that store (which is usually 1 mile/$ or 1% cash back with fat wallet et all.
If anyone has any thoughts, I'd love to hear them before I buy. Thank you in advance.