Yep I have the same problem on my laptop for the last week or so!  The stupid thing is if I go and google the the youtube video title it plays fine via the google search results!

news.bbc.co.uk is also broken for me along with a load of other flash video sites.

EDIT:  Seeing your post made me actually get round to fixing it, go here, run the uninstaller and the go to flash.com and reinstall it, all works again.