Looks like someone probably replaced the stator and they had the entire crankcase (stator) cover off and did a piss-poor job cleaning and reassembling it. Not sure exactly where that gouge is on the crankcase, the two pictures that look the same, but you are probably going to need to order a new crankcase gasket and get some Yamalube Yamabond #4 Adhesive Semi Drying Liquid Gasket and make sure to wait for it to "dry" before adding any oil to the engine. Based upon your pictures and video, I can almost guarantee who ever did that job, also stripped most of those bolts that hold the crankcase cover on, something like 11 bolts or so. Those bolts should only be torqued to 10Nm (7.2 ft lbs) which is not very much and EXTREMELY easy to over tighten and strip the case threads. You might want to be prepared to Heli-Coil all of those. A 3/8" torque wrench is too big and just not accurate for delicate work such as those M6 steel bolts into aluminum case where many don't realize a torque wrench isn't always for making sure it is tight enough, it is there to not OVER tighten. Find yourself a 1/4" torque wrench, like something used on high end bicycles. And then HOPE all that fixes the leak.