Sources have told us that, in the throes of their affair, John Edwards and Rielle Hunter made a sex tape that contains "several sex acts." And that his aide, Andrew Young found it on an unmarked DVD.

The tape, say both our sources, is explicit and reveals that Edwards "is physically very striking, in a certain area. Everyone who sees it says 'whoa'. She's behind the camera at first."

When rumors of the affair first broke Young was so loyal to Edwards that he pretended that he was the father of Hunter's daughter Frances Quinn, now 2. But part of Young's disillusionment with the 2004 vice presidential candidate and 2008 candidate came one day as he went through a stack of DVDs at Rielle Hunter's house.

It was this betrayal that prompted Young to write his tell-all book, The Politician, out February 2. Background: The New York Daily News reported last June that Young mentioned the existence of the tape in his book proposal. It's expected that he'll reveal further details in that story, and in the 20/20 interview to promote it, to air on Friday. "It [the tape] was kind of the last straw for people who had sacrificed savings and jobs to lie for John," said one of our sources. "You should expect to see plenty more stories about him coming out of the woodwork when more people realize how... complicated... his motivations were."

Up until he discovered the DVD, says one of our sources, Young's devotion was typical of the "cultish" fervor Edwards brought out in his staffers. This is why, says our source, who is close to Hunter, major media organizations could not stand up the affair story despite well-intentioned efforts. "They [staffers] would do anything to stop it coming out — they lied, they bullied, they called reporters' editors and bad-mouthed them, they exchanged access."

We haven't seen the tape ourselves, so if anyone has a copy they'd like to share, please get in touch.