If it sounds like a diesel (couldn't really tell from your video too much exhaust note), a rattle and clack-ity clack, Id bet it's the bottom end. I noticed the oil pressure was pegged. Did you maybe put the main bearings in upside down? They will run that way for a while, I saw one run that way for about week then it seized a rod. Sounded just like a Diesel. That's my Good luck and hope you find it soon.