I doubt that a video would help Matt, but without removing bits of trim or - Heaven forbid - the IP itself and getting down to the nitty-gritty of things I doubt that you're going to get to the source of your problem. Unfortunately sound is very directional and can travel through ducting and pipework, which makes finding the source somewhat challenging to say the least. The cabin pre-filter is on that side of the car and it may be worth removing and re-seating it to see if that helps.
I take it that it's only road-induced rattle and you don't get it with the A/C fan on and the engine either off or idling?
Jeff
I take it that it's only road-induced rattle and you don't get it with the A/C fan on and the engine either off or idling?
Jeff