Sloppy piston and gudgeon pin on MGB

I've had the car about 6 months, but not used it much due to Lockdown. When it warms up I get this light knocking noise at tickover. (not tappet noise).
It's a gold seal engine of unknown age, but had a new piston and valve fitted in 2016.
It hasn't done more than 1000 miles since then (according to MOTs).
What's the noise? Is it a worn cam follower? Is it the slightly loose piston/gudgeon pin? You can hear it most clearly in the bit of video from under the car. Oil pressure is 80 psi running and 60 psi at tickover.,
It turned out to be a piston that had been badly fitted to the con rod. I replaced the piston and rod (I got them fitted by proper engine builders, and put new bearings in for luck)

[@sickbastard82]

Od this noise constant and loud?

[@foleybrown]

It turned out to be a badly fitted piston which the prevoius owner had put in after a dropped valve. The press-fit gudgen pin was not central and they had tried to drift it back with a punch which had damaged the new piston.
I had to fit a new piston and rod, which solved the noise. The piston was properly fitted to the rod by a specialist using a press and a jig.