Why Silverlight? Why DRM?
Services like MSN video can't get the "big guns" -- there may be some decent stuff on there (I wouldn't know), but it's not blockbuster territory.
The big studios are scared of opening Pandoro's Box with "unprotected" downloads, so they need calmed with talk of DRM. Just as in the case of music, they are ignoring the fact that people who're into free copying can just download ISOs of a physical disc from the net.
But never mind.
Let's all just sit back and relax, because this is going to pan out exactly like music did.
They'll discover that there's an online market after getting fairly high sales through Tesco. They'll wonder why that market's restricted and ignore people saying "It's the DRM, stupid". The early adopters will upgrade their PCs/media players and discover how much hassle it is to reactivate. People will realise that they can't play them on the iPod Touch. All that sort of thing.
Bosses will *finally* realise that "It's the DRM, stupid".
Of course, both the technology and market are more mature now than in the early days of iTunes, so the cycle will be much quicker -- I reckon video downloads will be DRM free by 2012.