I might be mistaken but I think this is the only way, for now, to buy things on amazon using bitcoins.
You can also use Purse[1], and you can get discounts too! I've read decent reviews about it though I really haven't tried it myself. If only Amazon doesn't charge abysmal internetional shipping fees.
[1]
https://purse.io/Correct, actually there many vendors who help us to use bitcoin to buy good, service or even pay tuition. One of my favorite is purse.io . It seems the way it works is almost the same. And actually amazon don't really receive bitcoin but still recieve fiat, all transactions is managed by those vendors.