Is this the upcoming Google's 2013 flagship, Nexus 5?

We have just seen the unveiling of the lately announced Android 4.4 KitKat in a video, but with this very same YouTube video, something else too carried out. In a sequence, a man in the green t-shirt is holding a Nexus 7, like device in his hands.

But, the device in the above screenshot seems to be smaller than a seven-inch tablet, like the recently announced Nexus 7. Even though the phone looks no smaller than a five-inch smartphone nor larger than a seven-inch tablet, we expect that the company has accidentally leaked their 2013, Google's flagship device, the new Nexus (also known as rumored Nexus 5). The leaked device is pretty clearly visible in the hands of an employee from Google, with a horizontal 'NEXUS' logo and the Nexus 7 like matte finish on the backside. What else can we expect?