Grayson Questions Bernanke

Congressman Alan Grayson asks Ben Bernanke who received the half-trillion dollars that went to "foreign central banks" in the recent bailout. Bernanke replies "I don't know." [YouTube]

I've watched this a half-dozen times and can't make heads nor tails of it. Bernanke's apparent apathy about the figures Grayson's quoting seems scandalous but I could use an honest economist's commentary to untangle what it means to trade dollars for euros as Bernanke is describing. I would welcome any thoughts from the macro-economically inclined.