In a revised statement, Microsoft says it has "no plans" to introduce any Blu-ray add-on for the Xbox 360. But—despite the fact they watched the same video you did—they claim Ballmer was referring to the PC.
Here's the full statement:
Steve was referring to Blu-ray accessories for the PC. As we have said in the past, we have no plans to introduce a Blu-ray drive for the Xbox 360. In fact, the future of home entertainment starts this fall when Xbox 360 becomes the first and only console to offer instant-on 1080p streaming HD movies. With a library of thousands of TV shows and movies to choose from, Xbox 360 owners can instantly watch the movies they want, when they want, in the highest form of high definition.
This more clearly worded denial probably should have come last night, when we first asked for comment, instead of the more open-ended one provided at the time. Whatever... easy come, easy go. However, the idea that Ballmer was referring to the PC—which already has Blu-ray drives—rather than simply saying something that wasn't true, that's a little more questionable.
One more time, for posterity, this is what Ballmer said in reply to a question about putting Blu-ray in Xbox:
Well I don't know if we need to put Blu-ray in there—you'll be able to get Blu-ray drives as accessories.
Steve Ballmer Exclusive Interview Series:
Part 1: Ballmer Talks Natal, Says Blu-ray Add-On for Xbox Coming
Part 2: Ballmer on the Smartphone Race: "It Doesn't Matter What the Critics Say"
Part 3: Ballmer on Zune: Sometimes You Get It Right The Third Time?
Part 4: Ballmer on Those Crazy Ballmer YouTube Videos