From our underwater camera - Michael Phelps adds his analysis of how Leon Marchand's work underwater contributed to his gold medal count in the men's 200m butterfly. #NBCSports #swimming #underwatercamera » Subscribe to NBC Sports: youtube.com/nbcsports?sub... » Watch Live Sports on NBCSports.com: nbcsports.com/live NBC Sports Group serves sports fans 24/7 with premier live events, insightful studio shows, and compelling original programming. NBC Sports is an established leader in the sports media landscape with an unparalleled collection of sports properties that include the Olympics, NFL, Premier League, NASCAR, PGA TOUR, the Kentucky Derby, Tour de France, French Open, IndyCar and many more. Subscribe to our channel for the latest sporting news and highlights! NBC Olympics is responsible for producing, programming and promoting NBCUniversal's Olympic coverage. It is renowned for its unsurpassed Olympic heritage, award-winning production, and ability to ag...