2) However, he's not "complaining" about duplicates in those links. He's cross-referencing previous discussions in order to let people learn from them.
3) For what it's worth, he's been here almost two years -- you've been here barely half a year.
I read through his history and found this really cool submission: http://news.ycombinator.com/item?id=2878264 Computer Graphics? Or Real? "Ultimate Batting Practice"
Which led to the analysis of the video: http://m.wired.com/wiredscience/2011/08/exposing-a-fake-vide...
Which led to another analysis, "Water Slide Jump" http://m.wired.com/wiredscience/2010/05/preemptive-mythbuste...
http://scienceblogs.com/dotphysics/2009/08/more-on-the-giant...
It pretty much demonstrates just how difficult it is to apply mathematics to analyze real-world problems, which is really interesting and thought-provoking IMO.
Anyway, my point is, Colin has good taste, and you're doing him a serious disservice. He does good, helpful work, and I hope he doesn't stop, and doesn't straight-up leave, because the community would be worse off. I'd certainly be tempted to leave after reading something like what you wrote.