Amazon has sent out official invitations to an April 2 event that promises to offer an update on its video business. The slightly cryptic line is being seen as code for the grand unveiling of Amazons answer to Googles Chromecast and the Apple TV. Rumors and reports that Amazon has been developing a set-top box have been circulating for the best part of a year. At the moment, the industry seems to be agreed that Amazon is planning to launch both a simple streaming dongle (like the Chromecast) and a proper set-top box too — like the Apple TV and Roku — and customers can decide which one they want.