How warm was the engine when you made that vid? Sounds like a good bit of piston slap and a little odd but much more slap then I get from my street racer with big clearances starting a 10 above which I do every winter.
It also has some odd noises and it looks like the motor bucks a hair with the odd sound.
I would of changed oil sooner but you could still send in a sample and see if its fuel diluted or has coolant in it with little cost.
That was 2-3 mins after start-up. ~100F?
I haven't heard the valvetrain or "slap" this loud ever since I've had the car.
So, how bad would the problem be if it has coolant in it?