High Quality Content by WIKIPEDIA articles! RiffTrax are downloadable audio commentaries featuring comedians Michael J. Nelson, Kevin Murphy and Bill Corbett heckling (or riffing) films in the style of Mystery Science Theater 3000, a TV show in which Nelson was the head writer, and later the host. The RiffTrax are sold online and delivered by digital download. The site was launched by Nelson and Legend Films, now renamed Legend3D, in 2006 and is based in San Diego.