In a second video, also posted online, men from the gang in Whitechapel tell another man "no drink in this area, it's a Muslim area" before ordering him to pour away his alcohol.
Detective chief inspector Wendy Morgan from Tower Hamlets borough said: "The Met takes such homophobic behaviour very seriously.
"This man is a crucial witness in the investigation and we would encourage him and anyone else with information relating to this incident to make contact in confidence as soon as possible."
Additional police patrols are being mounted across east London to reassure the public.
A 22-year-old man was arrested in Acton, west London on Sunday, and a 19-year-old man was held after going to an east London police station on Monday. They have been bailed to return to police on March 12 and March 11 respectively.