The reason you shouldn't rely on device ID is because people buy new players and give away the old ones, so the unit S/N is not 1:1 mapping to account. Instead it is better to store a token in the registry when initially the device is linked to account and pass that. The registry would be deleted on factory reset or channel deletion, resulting in auto-unlinking of the device.
If i remember, there is no default certificates file, so you have to provide one yourself setCertificatesFile() (that may have changed - s/o correct me?):
video.Addheader("x-roku-reserved-dev-id", "") ' please re-read docs on this, 2nd param ignored for x-roku-reserved-dev-id'
video.SetCertificatesFile("pkg:/source/testCA.CRT")
video.InitClientCertificates()
