The clip runs just over two minutes and features a series of stylized vignettes that morph into brief snippets of gameplay footage. All of this is set to a cryptic voiceover repeating something about a circle still turning.
It's an interesting if slightly depressing look at what might have been. Head over to Kotaku for all the drama.
[Update: Steve Danuser, formerly of 38 Studios fame, has published a context-driven explanation of what's shown in the video.]