Re: Can't watch the video
"Possibly because, as I said, MS have made a video which I can't watch."
It's also explained in the article and on the linked site, though yes, it would be nice if they hadn't used Silverlight. (Though I'm curious what platform you're on that can't view Silverlight if you want to. It's available for Macs and Moonlight makes it available on Linux, I think).
"In this respect it is like CoffeeScript: you can't just ship it to the browser. Though I assume we can expect to release a version of IE that does support TypeScript and benefits from the kind of compiler optimisations that LLVM can't provide"
"I was suggesting the other way round: JS is being actively developed and, therefore, open to suggestions"
"It looks like Microsoft has come up with another niche language for its developer eco-system"