To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video Share Embed Share URL Video File Node URL Embed Code <iframe title="MRC TV video player" width="640" height="360" src="https://www.mrctv.org/embed/180296" allowfullscreen></iframe> Humans must "inhabit other planets," Libertarian presidential candidate Gary Johnson told ABC's "This Week with George Stephanopolous" on Sunday.