I'm thinking Samsung has exclusive rights to advertise for consumer electronics (or something like that) during the Olympics. (Keep in mind these ads debuted for the Olympics' opening ceremony.)
Therefore Apple has to advertise in a way that gets around these exclusivity deals. Therefore products are a no show.
One thing to consider is why Apple made this ad in the first place.
Since these ads opened alongside the Olympics, I am guessing it has something to do with Samsung being an official partner with the Olympics, likely with exclusive rights to advertise phones, TVs, computers and whatever else they paid for.
So, in effect, Apple may have been locked out from advertising their products during the Olympics.
The Metro UI is great, but the hardware on the market isn't exactly stellar (compared to iOS/Android offerings). If I were Microsoft, I'd be worried about something similar happening in the tablet market.
How are they going to stand out in non-traditional PC markets?