It was a separate sound from the lifters. The lifter noise is always there, the noise in the video stopped after a minute or so.
LETHAL O/R H, GEN2 OVER AXLE PIPES & GT500's
DRIVESHAFT SHOP ALUMINUM DS W/ BMR LOOP
MGW SHORT SHIFTER
CDC CHIN SPOILER W/ BLACK BILLET GRILLS
BLACK JLT OIL SEPARATOR