"Were you pissed off you had to do it or you just did what you had to do?" Gibney asks him.
"The latter," Armstrong responds with a laugh. "Maybe I'd approach the decision differently today, but at the time I didn't lose sleep over it."
Armstrong also further explained how he got away with using the blood booster EPO during races.
"The half-life of EPO is four hours, so back it off from there and figure out when you're in trouble," Armstrong says in the film. "My defense was I have passed every control you've given me. That's true. The samples that were given were clean."
Gibney said "the great tragedy" of Armstrong is that he continually justified what he was doing.
"He couldn't see the difference. He couldn't see the borderline between where the sport ended and the where real life began," Gibney said.
Much of Armstrong's life today centers on trying to keep what he has left. Three major lawsuits, including a fraud case brought by the U.S. Department of Justice, that seeks to strip him of more than $100 million.
"The last time I communicated with Lance was when I let him know that the film was going to be called 'The Armstrong Lie,'" Gibney said.
When asked how Armstrong took the news, Gibney said "not so well."
If Armstrong's reputation stands a chance at any kind of redemption, it will likely take a while.
"People don't like that truth as much as they liked the beautiful lie, and that's a hard thing for Lance to accept, because he found much more affection in telling the beautiful life than the ugly truth," Gibney said.