Anyone who voted for Obama and is going to vote for Clinton is going to to do because they felt that Obama has been a great president, and that Clinton will be more of the same. Not to mention both are democrats, and people most likely to vote for Clinton are democrats, who also voted for Obama.
Concerning black women, I guess that many African Americans feel that the democrats have done stuff for them. Your picture suggests that some might be followers, which could be the case. They may have wanted to get a minority in the White House, and now they want to get a woman in there. Just to break the all white male streak we've had since...forever.