Anyway, getting to Mars isn't the problem, we know how to do that. The problem is locating the spot on the planet where we want to land. These guys are using a camera to look at the ground and compare it to a picture they have on board. It will probably have to be a picture taken by a probe, nothing from Earth is going to have enough resolution. It's weird how much processing power it takes to recognize an image, considering that you and I do it instantly and continuously.
The best part of the video is watching the rocket motor twitch this way and that to keep the spacecraft balanced. All big rockets do this but you hardly ever get to see it being done.
Just for grins, codingame dot com had a programming puzzle that mimics this situation, though vastly simplified. It only operates in 2-D, the terrain mapping has already been done, and we have a fairly large area to land in. You can watch my solution play out here.