"Collisional models predict a lot more of these craters." -Patricio Salvador Zain

Did you know that the asteroid belt is one and a half AU (the distance between Earth and Sol) deep? And that all the big 4 asteroids including Ceres and Vesta have unique and distant orbits? There's a lot going on in the asteroid belt, but people overlook it. Not this speaker though, this LPI reveals the model all planetary scientists are now using.

• The slide at 2:00 demonstrates that the belt is divided into six parts, six separate neighborhoods, that are all in resonance, meaning the individuals will rarely collide with anything big. At least not naturally.
• At 6:10 we learn that Ceres is strangely depleted of large impact craters. That's what killed the old asteroid belt model. It's a direct discovery from the wildly successful DAWN mission.
• At 13:40 you see that Ceres is mostly impacted by objects from the outer belt, and second from Ceres' own neighborhood, the middle-belt. While Vesta the dominant asteroid/dwarf planet in the inner belt, is least impacted by it's own neighborhood, although all six belts are about the same. This has to do with asteroids still working themselves into a sustainable resonance. The ones that haven't got there are the ones most likely to impact something, and they most likely will come from closest to Mars.
• Conclusions at 16:20

Ceres and Vesta, along with Pallas and Hygiea, actually dominate their relative parts of the asteroid belt. It really is six different belts, not one. This is the tip of the iceberg though, studying the asteroid belt is a lot like studying the moons of Saturn and Jupiter. The more you look at it, the deeper it gets. 

This LPI was made because previous assumptions about the asteroid belt don't fit the observations. And you can tell from the speakers presentation, that the now updated model will still evolve with time and more observations.