hello, I have recently just bought a 6c Polo Gti and I love the car except there is this knock/rattle that i cant figure out! It only happens when the car shifts weight (over drive-way or bumps) and when accelerating from a stop or braking. It sounds like it's coming from the B-Pillar on the passenger side but i've already inspected that and can't figure it out. Anyone else had similar problems?

This video is a really good reference @ 19sec.
YouTube
19sec

someone pls help