A useful "Other Accessory" would be LEDs that could be mounted on the dash near the windscreen lower edge that repeated the turn signal flashing and were visible to the front camera. It would then be possible to prove that you were indicating correctly before a manoeuvre.  

At the moment only the audio recording can prove indication happened if there is an audible alert (but not the indicated direction).  Setting the front camera low to include the dash binnacle does not capture the turn indicators.