Open this photo in gallery:Microdramas are one-to-two-minute-long shows often filled with cliffhangers and shocking twists to keep viewers watching.Melissa Tait/The Globe and MailSave for laterSu Zihang doesn’t have an IMDb page, but if he did, it would be a long one. The Beijing-based casting director specializes in microdramas, one-to-two-minute-long soap operas that have transformed the Chinese TV industry and are increasingly popular overseas.Last year, Mr. Su worked on more than 20 projects, casting as many as 200 actors and extras at a time. “Most microdramas nowadays wrap filming in about a week,” he told The Globe and Mail. “Premium microdramas…