My suggestion is when the motion sensor is activated an audio announcmnet is made saying "Hello, Please be aware you are being recorded with a video camera on this device".
Why should this be done it may stop any potential offenders going any further but you are warning them they are being recorded and may make the video admissable in a court of law if it goes that far.
I know there are countries arounf the world that need this to be done.
You could do it as a pre-recorded message along the lines of the above quote or give the owner the potential to record is own message, this could be controversial depending on the type of message recorded it could be very impolite!!
This idea could be used on dorrbells, alarms, spotlights etc. etc.
You could also translate the message to all languages in order it can be used globally.
I have recently purchased a Ring video doorbel and at this point in time find t very usefull
You could also add a this feature into the Amazon Alexa app when the customer sets up "Motion Detected" and add a box to add an audio announcement, pre-recorded or otherwise?