Unfortunately things are not as exciting as Hryb described, at least according to the report by veteran NeoGaf user GrizzNKev, that tried the demo and came out less than impressed.
According to GrizzNKev the demo was running on twenty demo stations at the Xbox booth, some of which were inactive, with boxes hiding Windows 8-based PCs with Xbox One controllers attached.
Pausing the game shown the mouse cursor and the UI displayed keyboard keys. The game crashed to Windows 8 screens and upon death it shown a “Battlefield 4 at E3” splash screen, indicating that the demo is possibly just the E3 pre-alpha version retooled. The demo was also limited to 8 vs 8 players, which on the full sized map ended up being rather unimpressive.
YouTube personality TotalBiscuit also confirmed that the demo was running on high end PCs (including the detail about keyboard keys on the UI). You can check out his own video at the 3:36 mark. He also mentioned that the frame rate was a bit spotty.
At the bottom of the post you can see two very telling pictures taken by Reddit user DanTMWTMP.
Mind you, this definitely isn’t the first time that a “console version” of a next gen game is caught running on PC with controllers attached. Just to bring an example the “PS4 version” of Watch_Dogs was running in the same way at the Ubisoft booth at Gamescom, as I could personally verify, but at least in that case Sony or Ubisoft didn’t make much of a big deal of it, nor hid the keyboards, that were in plain sight.
Although this is really disgusting considering MS PR Chief said they'll show fans an Xbone demo of BF4 from the console itself running the game. Pretty low. It's like Xbox stans love to be abused by MS from paying Xbox gold, buying three to five Xbox 360 after they got RRODed etc.