Personally I've always got a bit wrong in most of he homeworks but usually felt that while I understood the material I didn't recite enough time to rigorously check my answers and rewatch the materials to pick up on some of the subtle things you need to remember or some questions.
The correlation will be interesting. Undoubtedly the top 1000 is made of many of the type of people that must be the best at whatever they try (not exclusively of course) and with a decent amount of time on their hands, after all there is no disincentive whatsoever for not completing something and no previously known reward for perfection (I guess a piece of paper can count). Given some wording in some of the Qs (actually my only complaint about this course) a lot of care must be taken to ensure that every question is right, so being in the top 1000 is no small effort.
That said I have a job I like already, and plan on using what I learned here.
Those 1000 with more time and drive to be the best probably are some of the best job candidates though. Plus chances are they do need a job after all.
Definitely learnt a lot, which surprised me because I did 3 classes that were based around AI and probability in my course. It has enlightened me a bit on the difference between a top of the range CS college and where I did my degree just it terms of how much ground can be covered and covered well.
So their metric isn't ideal for identifying passionate poeple ;-)