Zorro is described as 'utility to completely blank the screen except for a rectangular area selected by the user. This is especially useful for watching videos on your computer without being distracted by other programs'. There are three alternatives to Zorro for Windows. The best alternative is Cinemadrape, which is free. Other great apps like Zorro are TunnelVision (Free, Open Source) and psKino (Free, Open Source).
CinemaDrape helps you focus on your current task on the screen (such as a video in a web page, a photo or a document editor area) by instantly blanking or dimming the other less important areas in a web page or in the background windows.