This is US-only for now, but Amazon has taken its Prime Instant Video service to iPad as a native app. Users can stream films and TV shows from the company’s catalogue, as well as downloading them to the device for offline viewing. The app ties into Amazon’s Whispersync technology, enabling people to start watching a video on one device then switch to another without losing their place. It’s the latest in a series of deals and product launches boosting the credentials of Amazon’s service as a competitor to Netflix, Hulu and other on-demand rivals.