All that says is he is not going to run for the post of VP. No one has run for the post of VP in over a hundred years. That does not say he would notaccept the VP nomination if Hillary offered it.
He chose the words carefully. He was not asked if he would run for VP. He was asked if he would accept an offer from Hillary to be her VP. He did not annswer the question.
Hillary keeps saying she would like him as a running mate.. not saying if she or Obama would be at the top of the ticket. It is a way to try to force him to say he would not be her running mate. Then if she gets the nomination she can say I offered the VP to obama and he turned it down.
If he says yes, then he is done as a candidate for president. he would be running for the office of VP.
Hillary and her supporters in the media are just trying to put Obama in a box. Obama is trying his best not to let them do it.