I would guess they do to. Netflix recently moved to the AWS infrastructure for their streaming and it was recently revealed that Netflix accounts for 20 percent of all internet traffic during peak times. I highly doubt Amazon simply said "go read our webpage" in a situation like this.
They have to. I've never negotiated w/ amazon, but their list bandwidth prices were 3 - 4 times more expensive than what i got negotiating with CDNs and carriers directly.
That's to say nothing about cogent, who will sell you bandwidth at $4/mbps, AWS's cheapest pricing (at 150tb/mo) still comes out to $28/mbps, which is a joke.
