From what I can tell, there's no new technology here, nothing depending on fundamentally new science; rather, it's just clever use of current technology. The system covers the object to be hidden with hexagonal tiles that can be set to specific temperatures, so that in the far IR, they can be set to look like either the background or a specific programmed shape. In that video, they make the tank look like a station wagon, for example. ("hey... what's a Volvo station wagon doing out here on the battlefield?")
To blend in with the background, each sensor panel can include a camera that observes the temperature of the environment on one side of the tank (over a small area), and the system then programs the pixels on the other side of the tank to those temperatures. The results is like looking through the solid object. Much like this clever guy did with his Halloween costume: using two iPad2 tablets on either side of his body. The combined cameras and videos allow you to see what's behind him, as if you're looking right through him.
Invisibility is a subject that gets a lot of university research. The technology to do this in visible light is very likely many years away, but imagine light-piping (fiber optics) an image from one side of a cloak to another, so that the objects on one side of you can be seen as if you weren't there. I expect the first uses will be to disguise soldiers from being seen from great distances; it will be a long time before you could stand near someone and not see them. Unless you're over 65.