A group of tech-savvy activists have recorded hundreds of hours of rallies, but it was a four-minute clip that has brought them instant fame.
Made by the Social Record Association (SocRec), the clip showed a policeman throwing punches at a group of activists as officers approached them during last Sunday's protest against the government budget in Central, but it did not show clearly whether anyone was hit.
It has been viewed tens of thousands of times on YouTube, and became one of the most talked-about news stories last week when Commissioner of Police Andy Tsang Wai-hung questioned its authenticity.
That irked Paul Leung Yat-ming, one of SocRec's founders, who said his group strove to be totally truthful by making unedited videos and posting them on the internet.
'We care about the credibility of videos uploaded to our website and YouTube: this is why we decided to register as a society according to law instead of just publishing videos online anonymously,' Leung said.
'We believe: there is a video, there is truth.'