Amazon's a2z research and development subsidiary has 21 positions posted as it seeks to rapidly expand its team working on its MP3 store and Cloud Player, its rival to iTunes. It's looking for developers and engineers, a UI designer, engineers focused on  international development and project managers. Xconomy notes that the MP3 store has picked up steam with the rise of Android smartphones and often comes pre-installed. Cloud Player made its debut last year and is bundled with the MP3 service. It notes that while Apple's strategy was to use digital music as a way to sell devices, Amazon's strategy is to keep people engaged so that they just buy stuff — and Amazon sells a huge array of things. Yet Amazon has far to go to catch up with iTunes. Market research firm NPD Group estimates Apple's share of the digital download market at 70 percent, with just 14 percent going to Amazon. The e-commerce giant also is reported to be considering a standalone streaming video service that would compete with Netflix. Amazon's Instant Video service is free as part of the $79 unlimited shipping service, but The New York Post reports it's considering breaking that service out. It also says the prospect poses licensing issues with media companies. In a letter to shareholders, Netflix CEO Reed Hastings said it expects Amazon's move and for it to be priced lower, but he described Amazon and Hulu  as "quite small bidders" in the market for streaming content.