The quote in the post title, which appears at 3:34 in that video, comes from a GQ Magazine article from last November titled "Is This the Sanest Man Running for President?"
There is nothing he will not answer, nothing he will not share.... Johnson is fundamentally incapable of bullshitting, which is one of the many, many things that make him so unusual for a presidential candidate. (When a reporter asked him, after he gushed about how great New Hampshire voters are, if he says the same thing in Michigan, he replied, "No, Michigan's the worst.") He finds presidential politicking of the sort we've grown accustomed to—slick, scripted, focus-grouped, how-does-the-hair-look—to be "absolutely phony."
Another thing you need to know: He was never supposed to be the fringe candidate, and his campaign is no lark. Before he officially declared, he visited thirty-eight states—on his own nickel—to get a sense of whether he'd be a viable candidate. He was the first GOP candidate to announce, in early April, and for about twenty seconds seemed like a contender. The wildly popular (still) two-term Republican governor from a state that is two-to-one Democrat. A guy who's confident that he knows how to manage the purse strings and balance a budget because he did it—eight years in a row—in New Mexico. His fiscal conservatism is unmatched by anyone in the race. And his socially liberal cred—the only pro-gay and pro-choice Republican candidate—is unmatched even by some Democrats. (Of course, while this could be an asset in the general election, it's a bitch of a liability in the GOP primary.)