I have done a bit of research, and I can't seem to find out what caused that 180 degree change in his entire world view...

All that seems to pop up about the issue is: "My own research made me realize I was wrong about Hillary and the Clintons." That is about the most absurd reason I have ever heard.

http://www.politico.com/story/2014/03/david-brock-bill-clinton-hillary-clinton-104976

Death threat? Blackmail? Money? Children???

EDIT: Since he was married to Alefantis, we should find out what made him have his "change of heart" so that we may use that as leverage against him (if needed)