This video comes courtesy of Paul R. Brian.
The police were apparently very unclear about what the charges (if any) were. They raided the pub in force and at least one other attendee (or organizer) was led away and possibly detained.
Originally, the police didn't detain anyone but simply tried to intimidate people by gathering information.
However, after that, according to Brian,
"Richard tried to help by telling everyone to leave, which is when police said "You can't leave" and demanded passports and ID from everyone. Eventually after some time Richard was shown the door and apparently detained. He came back in police vehicle and told us he may be charged. But said he did not know what he would be charged with."