It was reposted today because he gave the talk again this morning at Pycon Canada, I suspect.

Are you sure these are all the same? I can't check from here (on my mobile, poor reception) but the URLs look significantly different. This one is a slide deck, one of the ones you quote is a video.

Added in edit:

It does look like this one - http://news.ycombinator.com/item?id=4651882 - really is a duplicate, but it got no votes and no comments, so perhaps a repost is in order.