I finally got a Tesla Boombox feature working on my Model 3, almost a month after release...maybe because of the cold or maybe just lack of time to sit with a computer and get it figured out. Anyways, I made a short instructional video on how to format a single USB drive using Windows 10 for both the Tesla Dashcam and Tesla Boombox. Well actually all three, when Tesla Track Mode is included in the mix.
There is a subtle trick because Windows cannot format two exFAT partitions consecutively.
Here are the manual instructions illustrated by screenshots: