I need help i have strange rettling noise, engine is working fine and no vibration on car... I dont understand where sound coming opening engine hood its sounds okey and  cant hear this noise, only you can hear seting in a car, i put in video to understand.

https://www.youtube.com/watch?v=Dh_OWoCn6Qk&t=4s

Welcome to the forum, you'll find the members on here are a friendly and helpful bunch 😊

I've watched the video but struggling to here the exact noise your referring to. But I am aware that the 2.0tdi engine on b9 a4 can get louder when the vehicle dpf is doing a Regen. What kind of driving do you do mainly for your commute to work? 

Also if the cambelt has slipped a tooth then this could cause a rattle and louder noise. Obviously the cure is a new cambelt and cams realigned if it is that. 

The car I suspect is still under warranty and as such I'd get it into a dealer. 

Cheers

Steve