Meh, does not matter. I rather keep the yearly subscription, anyhow. I order stuff from Amazon all the time.
For those asking, while Prime Instant is a nice bonus, it's not good enough to replace Netflix. While there are many shared titles (e.g. Star Trek, Epix deal, etc.), and even a title or two on Prime Instant that is not on Netflix (e.g. Degrassi, Gilligan's Island, Coneheads, etc.), there is a lot more content that is not on Prime Instant that is on Netflix. Also, Prime Instant is missing features, like "Recently Watched", and such.