Startup Higgsfield AI caused a stir in May when it released its 95-minute AI-generated film “Hell Grind” at the Marché du Film at the Cannes Film Festival. While it was criticized for its nonsensical plot, the film impressed some audiences with its stunning technical visuals. And now it’s letting people in on the prompts used to create the movie. The San Francisco AI startup launched Higgsfield Academy in August, opening up the techniques used t…