Aside from all the interesting ways of defining privacy I never thought of before, the implications of the presenter's goal (making everyone happy to use social networking for almost all of their life) struck me the hardest.
Let's say some radical changes came about so that almost any reasonable person would feel free to post all their personal data on facebook, knowing that sensitive parts would be kept to specific groups. That still wouldn't take care of what I see as the biggest lurking concern; how our data will be handled in the future.
It's certainly paranoia, but we've all seen good companies turn to shit, and people have even seen stable countries turn bad. If a database of everyone's un-self-censored private data existed, it would have untold implications. Even now, it's staggering to think about. I don't know, I guess it's getting late and I'm sleepy. But I think about FB's extremely high valuation and wonder if something like that could be a seed of instability that would allow for decision makers from unknown vectors to influence how FB uses its data and stuff like that.