The first punch to the chest was met with a step forward, the second and third facing the face with raising the chin. The fourth, when fifth, seemed to knock him unconscious.
But when he came to his feet, and with his hands held behind his back, he again met the attacker again, and again and again, a symbol of what was largely peaceful opposition to an increasingly authoritarian force.
The striker appeared to be exempting one of the many "Lennon Walls" in Hong Kong, which is addressing unprecedented political concerns about the erosion of civil rights in the semi-autonomous region of China.
We'll tell you what's true. You can form your own view.
The walls, which have begun to appear over the city in recent weeks, are plastered with colorful notes protesting against a extradition bill declared "dead" by the government but still not officially revoked.
The video was shared earlier this week by Edith Leung, a member of the Hong Kong Democratic Party, a Left Party and the third largest in the Legislative Council. The link to the legislative council building in Hong Kong is seen as covered by graffiti after it was stormed. Getty
The link to the legislative council building in Hong Kong is seen as covered by graffiti after it was stormed.
It shows a man who is repeatedly punched by an elderly man who later tears down dozens of notes plastered to a wall in Kowloon Bay.  A number of people watched as he was later led away by the police.
"What the hell is going on? This is crazy!" Leung wrote before he later appealed for the victim's uncle to witnesses.
Ray Chan, a former Hong Kong parliamentarian, tweeted: "In Hong Kong, pro-Cops & pro-China thugs are just around the corner of your neighborhood. The young man really showed courage and wisdom when he defended the Lennon wall."
Hong Kong's human rights shareholder Johnson Yeung described the video as "painful to look".
"I greet the young man who did not fight back or back from violence. He was beaten 13 times by the pro-Beijing man in his face, and he did not turn back, he said.
Young people have been at the forefront of huge rallies over the last few weeks against the extradition bill, which would have allowed the suspects to be sent to China for trial
Activists have pledged to continue the pressure until Hong Kong leader Carrie Lam officially charges the bill.
Wang Zhimin, the Chinese government's chief representative in Hong Kong, said the Beijing government strongly supported Lam.
Rejects talks to free protesters arrested. He said it would be "a widespread challenge for rule of law in Hong Kong. "
" As for the latest series of violent incidents, all Hong Kong people, including those present, have expressed condemnation, "he said in a speech to Beijing loyalists in Hong Kong.
The protests against the proposed extradition legislation have given cause for fear that Hong Kong loses the freedoms guaranteed when the former British colony returned to China in 1997.
Critics fear suspects would face unfair and politicized attempts on the mainland, and that the critics of the ruling Communist Party should be directed.
On July 1, the 22nd anniversary of Hong Kong's transfer from Britain back to China, a peaceful march drank hundreds of thousands of people but was overshadowed by an attack on the area's legislative building.
A few hundred protesters searched the building, spray painting slogans on the chamber walls, swinging furniture and harmful electronic voting and fire protection systems.
Thousands of people joined in on the last call on Sunday and tried to bring their protest message to those on the mainland where state-run media have not covered the protests to a large extent.
Additional Reporting by the Associated Press