u/jarchuleta3

EDIT

Discovered the problem! It's the harmonic balancer. The weight has slipped off the hub because the rubber ring broke. Someone in the comments noticed the movement in the video. Thank you all for the help!!

Does anyone have any ideas what this sound might be? Never had this before. Doesn't sound like engine knock to me as it's too slow and clunky sounding compared to what I've heard before in other engines.