Besides being a rapist, why on earth did he leave his phone unlocked. Talk about an idiot.
And going back further why even video your rapes? I know we are talking about a mind that is alien to us here but why? Ego? Wants a record of his crimes? Does a video like that have some value amongst his ilk?
I suspect he wanted to get caught. Many of these sickos live in private hells that a part of them wants to get punished for to be made to stop.