The node he uses at 10:00 “Get forward/Backward”, the uploader says “You can add another float variable and set it with action value Y from EnhancedInputAction IA_Move. Use this variable instead of get move forward/backward node.”
Right click anywhere on an event graph to open up the context menu. Type Begin Play. You should see the node in the menu. Click it. Either you already are using Begin Play and it’ll take you to wherever in the graph the node is located OR it will place down a Begin Play node. You can also check out a fresh Third Person project and look inside of BP_ThirdPerson to see how player inputs are programmed.