This is Your Life: Duke Kahanamoku Hawaiian Olympic swimmer who won three gold and two silver medals. He is also considered the father of surfing due to his promotion of the sport, greatly increasing its popularity. First broadcast live on NBC TV on February 20th 1957.
You can stream This is Your Life: Duke Kahanamoku (Father of Surfing) (1957) free and legally on OldReel, via the Internet Archive.
Yes — it is in the public domain and can be watched and shared freely.