Your second video pretty much tells the story. You have very little oil pressure according to the gauge on the dash. I suppose many engines have lived a long time with only 5 or so pounds of oil pressure at idle, but when you revved the engine up the gauge did not budge. You have no oil flowing to the rockers. I think your noise is internal in the engine. Time for exploratory surgery. Start with pulling the oil pan and checking the bearings. There is a good chance the pickup screen on the oil pump will be at least partially plugged with silicone
