Tried to embed yesterday (with the usual [youtube ] nospace notation) and it didn't work - and now today I'm looking at things that were embedded yesterday and today they are not - just blank boxes.
It appears to be down. I looked at the code that you posted and it was done properly so I don't know what's up with that. I'll check with my host server admins.
this thread (and others) worked fine for me from home yesterday and are still not loading from work. So I'll blame it on old IE/work connection/voodoo :0