For the sake of accurateness: the deal where he sold the film rights for
LXG would of course have been a lot more recent since the comic only began publication in 1999, but it still most likely would have been a deal made before he'd seen the results of any film adaptations of his work. It was the one-two punch of
From Hell in 2001 and
LXG in 2003 that soured him. He's never seen
V for Vendetta, but has read the screenplay.
According to Don Murphy he tried to get Moore involved in protecting his work and guiding it in a way he saw fit in the adaptation to film, even offering to let Moore write the screenplay for
From Hell, but Moore had a "just give me the money and don't talk to me anymore about the film" attitude.