This is a Public Relations type film and really does not have much substance to it; nor is it partucularily interesting.
According to Wikipedia (take it for what it's worth) Walker enabled the Russians to decipher one million encrypted Naval messages. Enabled the Russians to track at all times all U.S. Naval Submarines. Told the Russians how the U.S. was able to track Russian Submarines so they could devise counter-measures. And so on and so forth.
After being arrested for burglary Walker was given the option of going to jail or enlisting in the Military. He enlisted in the Navy in 1955.
At
06:35 apparently that is a KL-7 "Adonis" Crypto Machine (?). Often used as back-up when radio propogation conditions were poor and would not allow electronic digital cryptographic machines to be used.
Dirk Rijmenant's Cipher Machines & Cryptology Site (Award Winning) has a KL-7 simulator as well as a wealth of information.