This is the trailer of the film about a scuba-diving expedition to Lake Khovsgol in Mongolia. Along with locating two wooden shipwrecks from the 1920s, the team may have come face to face with a lake monster that lake area residents refer to as “The Underwater Deer.”
You can find out more about the film at Strange Media, amd more about scuba diving in Beijing and elsewhere in China at SinoScuba who organized the diving expedition to Mongolia.