also, I like to watch videos of jeeps off roading. What exactly is happening when the vehicle itself stays level, but the wheels are crooked?
Lift kits do allow the axles more room to articulate, but most owners put them on to clear much larger tires, up to 38'. Larger tires bridge ruts better, give more traction, and lift the differential higher to clear obstacles. Some owners don't even lift, they just cut out the fenderwells. They understand more lift moves the center of gravity higher, causing the vehicle to be less stable on steep inclines. Tires do that too, but if they clear, don't lift. It's just for looks at that point, and will actually make the vehicle less capable. When the vehicle is level and the axles 'crooked, you still have traction and can move. Independent front suspension SUV's and trucks won't do as well because the minivan-like halfshafts restrict the wheels ability to conform to terrain. It's called articulation, and all the older manufacturers used to do it that way until the surbanites buying SUV's insisted on cushy rides. Now only Jeep makes them that way, and live axle vehicles still dominate offroad.
A Suspension lift is usually a kit that has longer springs that puts the body/frame further away from the axles. Which is preferred over a body lift which only seperates the body from the frame. A suspension lift also provides more suspension travel. Which leads me to your next question. What you see those Jeeps doing when the tires move but the body stays fairly level is called flexing or articulation. All suspensions provide this movement but it depends on the suspension design as to how much flex it has.
