What's this engine noise? Vanos rattle or timing system issue?

[jac]

At around 42 seconds after a cold start, I always hear a sound that is out of place, that coincides with the RPMs having gone down from 1K to just under 500 RPMs. It sounds like a marble bouncing around :-)

The sound does not seem to happen during driving, I can drive slow, normal or push the vehicle and I don't hear the noise.

I have isolated it to the area where the top of the valve cover meets the Vanos.

I don't think this is the "vanos rattle" issue, could it be a timing system (chain, guides) problem?

I have this video on youtube where you can hear the sound.

https://youtu.be/yPwr4Nv6QtE

I did work on the vanos a few months back and did the timing and have no codes... I'd appreciate some help :-)