“The Red Dragon” has uploaded a video on YouTube, which you can watch above, that demonstrates the Kinect 2 features in the Xbox One version of Battlefield 4. As previously revealed the Kinect 2 features are head tracking for looking around (although it turns out it’s only available in vehicles for some reason), body tracking for leaning and speech recognition for voice commands. He doesn’t actually demonstrate the voice commands in the video though, just talks about them and shows the list of commands. Also, if you don’t want to move your head around as much as he does for the head tracking you can increase the sensitivity in the options so that you can make subtler movements.
Here’s another video from YouTube user jackfrags, he includes a few voice commands in his video but unlike the previous video he doesn’t show himself playing so you don’t get to see exactly how the motion controls work, which is why I posted The Red Dragon’s video first.