The Guardian picked up the story:
When asked during a campaign event in Deerfield Beach, Florida, whether he would "pursue the violations that have been made against our Constitution by the present administration", Biden answered in the affirmative.
"We will not be stopped from pursuing any criminal offence that's occurred," he continued, going on to praise congressional committees for the deliberate pace of their inquiries into alleged Bush administration misdeeds.
But then, here is a video of a Fox interview where Biden explicitly denies the Biden/Obama administration will go after Bush (about 5:00 minutes into the video):
"“That’s not true. I don’t know where that report’s coming from,” said Biden.
Joe, it's coming from the other Joe Biden that is running with you for the co-vice-presidency position.