He had pleaded guilty to encouraging or assisting the rape of a six-year-old boy and admitted six charges of encouraging or assisting the showing of indecent images of children.
During the live stream Williams sent messages to the rapist instructing him to “put the sound on” and to “prove it’s live” by “smacking” the victim and making him “say hi”.
He also sent messages telling chat room users that the rape was about to be streamed and encouraging them to join him in watching it take place.
The rapist who broadcast the attack, a Pennsylvanian named William Chandler Augusta, was detected by the Canadian authorities and arrested in the US in February this year.
He was later sentenced for a range of offences to a term of up to 30 years in jail.
Philip Crabtree, 35, of Newcastle-Under-Lyme, pleaded guilty to 12 offences and will be sentenced at Stoke Crown Court on a date to be set.
Christian Johnson Lueking, 36, of Raynes Park, London pleaded guilty to one offence of encouraging the showing of indecent images of children and will be sentenced at Kingston Crown Court on August 18.
Colin Radcliffe, operations manager at the NCA’s child exploitation and online protection (CEOP) command, said: “These men thought they’d found a corner of the internet where they could avoid the consequences of participating in abuse.
“They were wrong and others like them should know NCA officers have skills and tools that mean no one seeking to harm children is safe from the law.
“Protecting children is an integral part of the NCA’s mission and our officers are dedicated to ensuring people like these are brought to justice.”