It seems the last Adobe Flash update (10.3.181.34) has some issues that has rendered all youtube videos broken to anybody who has updated their latest flash player update ...
I have found a simple workaround until ADOBE fixes their shit ...
Simply add an "
s" to "http" to make it
https:// in the URL and they will play as usual ...
Your Welcome
PS - if adding an "s" to the http is to hard for you, you can uninstall flashplayer 10.3.x and flashplayer plugin 10.3.x and try to fiddle around with previous flashplayer versions that can be downloaded
HERE