Chromecast is a new invention by the boys down in Google R&D (think of saying that in an old timey radio announcer vocie). It'll revolutionize the intertelevisiontubes!
If you are trying to run your image on a normal computer, laptop, or netbook (one that didn't come installed with Google Chrome OS), follow the instructions in this section. Said another way:
The Ninja authoring tool is a Google Chrome app for designing keyframe-based animation with HTML5, including 3D scenes and vector graphics. These scenes can incorporate components built on the Montage framework (see below), and the editor itself is built using Montage. Ninja includes a familiar set of drawing and layout tools, such as the Pen and Brush tools for creating graphics, shape primitives, and the Tag tool for creating page structure ( or tags, for instance). Graphics you create in Ninja can be rendered in the browser with either the Canvas 2D API or WebGL.