The images come "from Russia with love," while the video was posted by smartphones.sfr.fr.
Some questioned the veracity of the video as it shows the OS as being labeled KeyLimePie, but that is what the next release of Google's mobile platform was reportedly called, before it was changed to the chocolate-centric KitKat. The next version number, though, is still expected to be 4.4.
Specs for the device are still unclear, although it is expected that LG will be the manufacturer working with Google. Google's Nexus devices are developer devices, and as such are stock Android, without add-ons such as Samsung's TouchWiz or HTC's Sense, which make ROM upgrades more difficult.
LG was behind the Nexus 4, but that device was somewhat disappointing as it did not included true 4G LTE support. It did include HSPA+ which, considering its low price, was sufficient for many. It's unclear if Google will up the storage on the new device; the Nexus 4 shipped on the low end with only 8GB of internal storage and no microSD support, but for $199.
The Nexus 4 came with a 4.7-inch screen, so it will be interesting to see if the Nexus 5 comes with (wait for it) a 5-inch screen.