Haven't heard for sure, but I think he was getting fed-up with the flack he was taking from some of the lurkers.
It takes time and effort to post movies, so as a lurker if you don't like a vid and its not illegal, be decent just move on to the next one. Slamming posters accomplish little except driving the posters away; then again, maybe that in itself makes some people feel big.
Kitt5000 pretty well saw this board through its growing pains - hope he comes back.
Just my two cents.