I was there, and that was exactly how most of the audience did react after 15 min. into his talk.
He did not make that claim out of thin air, but produced documents that were publicly available.
The New Yorker provided more details on this topic in a piece they did on Paglen:
"More than fifteen hundred documents were made public in the case: invoices, e-mails, cell-phone logs, receipts. These contained financial data—a typical rendition itinerary seems to have cost the government about three hundred thousand dollars—and structural details of the rendition program."
Source: http://www.newyorker.com/magazine/2012/10/22/prying-eyes
The article also notes that he is recognized by other journalists for his work on renditions.