Legacy 2003 2.5 115kw piston slap cold start at -15c/5f?

[Dsmol]

I just bought this legacy, 190 000/118 000 miles, this is how it sounds @ cold start, this sound lasts for around 1-2 minutes. Also it slowly leaks through the gaskets, I was about to fix them at the shop, but now I'm not sure if I should invest when I heard this in the morning. Any ideas? Nevertheless car drives amazing, power is not lost, video how it sounds is below:

 

I found identical sound from other car and it was defective timing belt tensioner, video below

and even more identical sound: