In 2010, when Netflix was still early into its shift from DVD rentals to online movies and shows, it started using Amazon Web Services, the retailer's cloud computing division. Now that Netflix streams 100 million-plus hours of video every day, it's sticking with Amazon partly because of Amazon's scale and features, and partly because switching vendors "would be a significant multi-year effort," says Yury Izrailevsky, Netflix's vice president for cloud and platform engineering.