Mars Curiosity Rover's landing explained

Earlier I linked to an animation of the planned landing of the Mars Curiosity Rover landing. It involved a complex series of steps involving parachutes and a rocket that lowered the Rover to the ground on the end of a cable.

Above is a video in which engineers explain the various stages of the landing, and why they are doing it in such a complex manner. It all boils down to the difficulty of landing such a heavy and delicate machine in the thin Martian atmosphere.

As an aside, they stress that everything needs to go precisely as planned, so I found it a little alarming that they screwed up their subtitles starting at the half-way mark. I know it was a graphics agency and not the engineering department that put the video together, but still...
 

Mars Curiosity rover landing animation

Above is an 11 minute NASA animation of the Curiosity rover mission. Of particular interest is the landing sequence which involves a parachute descent which eventually releases a little booster that hovers over the surface and deploys the rover Curiosity by lowering it with a cable.