HONG KONG — Two Hong Kong police officers were arrested on Tuesday after a video appeared to show them hitting a 62-year-old man in the genitals, stomach and face while he was strapped to a gurney in a hospital in June.

The man was not a participant in the protests this summer that have often ended in violent showdowns with the police. A pro-democracy lawmaker who released the footage, Lam Cheuk-ting, said the man had been accused of attacking a police officer while drunk.

But protesters and their supporters tied the episode to one of their central grievances: that the Hong Kong police have used brutal tactics.