Many sites are reporting and there's video of Dre himself saying it. Its as official as it gets until the deal is actually done.
Another factor to consider is that if Dre signed an NDA clause and still let the video leak, it'd mean Apple has the power to pay less than the supposed 3.2b, but I doubt Dre is dumb enough to let this happen if he did actually sign an NDA. Either way, this is gonna happen.