Just for some context on the belt, supporting it being considered an outlier: Yellow belt was in major flux within days of that sale. It was still less than a month after the misc update, and within just a few days of the last accepted suggestion (raising the price from 20-24k to 2.0-2.5b). Pretty easy to handwave that one away, since it was already an outlier on the value. No idea why that guy was in such a hurry to get the belt.

Anyway, the discussion for that last trade looks like it's here, and covers how quick the belt owner was to jump on that deal: http://www.tf2outpost.com/trade/19524507