I wanted to watch Apple's iPhone 5 product design video again this morning so I went over to YouTube/Apple, found it, clicked "Play"... and was greeted with a pre-roll ad for the Verizon BlackBerry Z10.
Apple has no control over who buys or gets assigned pre-roll advertising on their YouTube videos -- that's all Google -- but Apple does have the ability to turn off pre-roll ads for the video in general. I can't imagine, even on millions of views, Apple gains any significant (for them) revenue from pre-roll ads on their videos, so turning them off would not only prevent competitions -- and carrier partners like Verizon -- from hijacking their viewers, but also protect their brand in general.
BlackBerry Z10 probably won't reach iPhone level sales any time soon, but what if it were Samsung buying those ads for the Galaxy S4? (Maybe they have already?)