Noise + vibration while back-pedalling. Should I be worried? Recently I noticed I'm getting a bit of noise and vibration through the drivetrain if I backpedal on the largest sprocket at a reasonable speed.

There is enough vibration that when I'm stopped at lights getting into position the whole bike vibrates.

I looked at the chain while the bike was on the stand and it looks like the lower segment is jumping up and down while the bike is on the stand back-pedalling unless it's really slow.

It looks to me like the top jockey wheel might be putting pressure on the largest sprocket. 

The chain is at basically 0 wear, and has been running fine for a while. 

Recently I changed lubricant from a paraffin wax + paraffin oil 1:1 blend to 100% paraffin wax.

Apart from the noise &amp; vibration the bike seems to be running fine.

If you're interested in the sound &amp; behaviour here's a short video: 

                
            

You can hear the vibration when the back-pedal speed increases 

Is this something that requires maintenance to correct or should I not worry?
Your video shows that the problem resides in the position of the derailleur. The RD is much too close to the cassette. The jockey wheel almost touches the large sprocket.

Use the B-screw to move the upper jockey wheel further away from the sprockets.