yeah, not sure what i hear, it doesn't sound like piston slap as i thought i heard on the vid sent to my phone ???
do a compression check and leakdown test, for headgasket failure.
then you're gonna have to start pulling covers to investigate, could be the oil pump running dry ?,
while you have the clutch cover off, remove the white plastic gear that runs the pump to disable it completely
check kicker gear operation
check under stator cover for flywheel rub/wobble