The Inforarium — the greatest source of illicit information in recorded history — is compromised. The Doctor appears in a hologram — "Who the hell are you?". He tells a guard that he will be erasing all traces of himself from their database, making everyone forget what they've heard through means he'd adapted from the Silence. At the end of the message, the guard completely forgets the whole ordeal. Then it replays... "Who the hell are you?" (thetvdb.com)