In a Canadian scene played more than 630,000 times on Chinese social media platform Weibo, a masked supporter of the Hong Kong protest movement strides towards two people in a Vancouver area shopping mall, is seized by police, pinned to the ground, then marched out in handcuffs.But the takedown last Saturday in Richmond, British Columbia – celebrated by the video uploader, who decried the “poison” of the Hong Kong protesters – was part of a complicated mini-drama with many moving parts, other…