The Discovery Channel’s “Mythbusters” series averages about two million viewers per week, and it is in the process of selecting a new host. One of the four potential hosts is Tucsonan Martin Pepper, the 1993 NCAA 100 butterfly swimming champion at Arizona, and a UA Sports Hall of Fame inductee. Pepper, who earned a doctor’s degree at Arizona, has produced and generated science-related shows for the Discovery Channel and History Channel. He began his “training” by filming nature scenes at Gates Pass and Redington Pass, developing them at home into professional-caliber products. On Saturday night, Pepper was featured in the series’ “Finale Show.”