Shifter rattle dura ace di2

Any chance of another video?

I had a similar problem that was caused by my brake cable not holding the lever tight in the body. The spring in my rear brake was dodgy so every time I pulled the brakes it left the cable a little slack, resulting in rattling. Check your brakes are releasing properly and/or that your cables are running freely in the outers.

Just check it's not the cable ports on the shifter. I had the same thing and it was driving me round the bend. Turns out I'd forgot to tighten the lids down when changing the cables. If you peel the hood back you'll see two tiny Phillips screws.
Sounds like cables though. Had that aswell and fixed it by retaping the bars.
My main cycling equipment goal is not too have a £4000 frame with £2000 wheels, it's just to have a bike that dosn't make a really annoying noises for at least 6 months..

Ah just noticed you mention Di2. Don't know anything about that or what the differences in cable set up are with mechanical..

If your brakes are cable then it's probably inner rattling against outer. Other than adding a grease on the inner cable to dampen it going to be difficult to cure. Maybe adjust all the slack out of the brakes might work