There's some very interesting things in that video. It set me to thinking about things Facebook isn't actually doing that Zuckerburg says he cares about. Which are things worthy of some further thinking to see what opportunities exist there...
In my experience, the comments on the niche subs are of considerably higher quality than the default subs. So much so that I'm puzzled what you could be thinking about. Can you give some examples?
A laudable goal, but for what definition of "constructive"? And PLEASE don't tell me that you guys think it will be the same definition for every site.