I find it to be a peculiar business decision to completely (as much as you can) migrate to one of your largest competitors' cloud service. It seems like Microsoft is the only, of the larger cloud providers, that doesn't -really- compete with Netflix. (Google has YouTube, and I guess even Microsoft has a much smaller Windows Store presence.) Even if Amazon can't access the raw data, they could see how you're utilizing…
So you're saying Amazon is going to risk millions of dollars so they can make a few more bucks on video streaming, which is like 3 levels down from their primary business?
Prove it. I had an argument with my last company about this very issue. If Amazon's primary business was video delivery, then that would make a lot of sense. But where does Amazon's primary revenue stream actually come from? That's right, it's AWS. Amazon may be an excellent retailer, but they spend just as much money as they make on the shipping and fulfillment side to get shit on your doorstep faster and cheaper than anyone else out there. Each person that spends money on Amazon can only really spend a few hundred dollars per year. But even a small company that's entirely hosted on AWS, like 70% of the companies I've worked for, pays Amazon thousands of dollars per month for hosting. There's definitely more people than companies, but shipping stuff to people costs a lot more money than Amazon needs to pay in order to have your stuff hosted by them. Plus they do a lot of R&D into making their own systems faster and more efficient, eventually passing savings down when they re-work their pricing tiers.
Basically, my argument is/was that the whole idea of Amazon stealing your IP to make a few extra bucks on whatever they happen to be doing is totally bunk. Amazon is really in the infrastructure business, and if you're a video startup...you're NOT. And take it from someone who watched a company try and fail to build a competing private cloud with no budget and a skeleton crew...it's stressful and not fun at all.
The main reason to use multiple providers is, as you said, uptime and redundancy...and "not putting all your eggs in one basket", so to speak. It's an engineering, not political, decision. My last company could have probably saved themselves by moving everything to AWS and shutting down their Level3 internet-backbone connectivity and direct fiber from the office to the datacenter (which is the same technology AWS is using anyway, except they have an actual cloud API and not just a pile of servers), but they were too busy conflating this engineering/performance decision with one that must be made for political reasons.