Mk5 GTI 2005 interior rattle

[Folmann]

Hey everyone, I've got a 2005 MK5 GTI and there's this annoying rattle noise coming from somewhere inside the car. I've already tried tightening all the bolts around the area, and it's not coming from the vent itself. Any ideas on what else it could be? I've searched through other posts but haven't found a solution yet. Thanks for your help

Video of the sound:

i=gAZHqE1TOHLBjZaC

[TheBALDpuma]

It sounds not dissimilar to the fuel line rattle - but that sounds like it's coming from the driver's footwell?  But infact it's under the car.