Update: Obsidian has said that the footage is indeed real and from an early version of the game. "Just to be clear, this is from an extremely early pre-production build," says the dev.
Last year the developer confirmed it was no longer working on the game, and will instead be pointing its attention at Alpha Protocol and Fallout: New Vegas.
The 'leaked' footage looks very early and very dark. In fact, if this is the most exciting part of what was developed at Obsidian, we can't say we're surprised it got the chop.