Having listened to all three video's I can almost certainly agree it is not a little end as it would rattle harder upon revving.
It reminds me of a hydraulic lifter. I had a Vx Nova saloon (I know, but holy sh!t it could corner, far better than the hatch versions). Anyway, one night in Skye, I pulled into the filling station in Broadford to fill up and for some obscure reason, I over revved the engine and was rewarded with a similar nose to the RR there and drove home convinced I had ruined the engine. Imagine, all the way to Inverness in the dark, p!ssing rain, with deer looming ahead and waiting for the engine to expire. It rattled it's metal mammaries all the way home and I parked it with a heavy heart
Next day, I went out to take it to my lock up only to be surprised as hell when it started with not a peep of a rattle
Seems I managed to jam one of the lifters which stayed jammed all the way home but when it cooled it came free. Mad!
(the RR also sounds like (don't laugh), the vacuum pump on my friends old VW LT van. It rattled like charity workers taking over the street, but pump the brake pedal a couple of times and it would die down for a few seconds... The vacuum pump was worn and they are known for this)
Anyway, if this engine version has hydraulic lifters, could one of them therefore be jammed with carbon or a bit of dirt partially plugging the oil hole? I wonder if removing them all, bathing them in Kerosene for a 24hr period would help, then a couple of oil changes (change oil, drive 500 miles or so then again.