OK I noticed that on a couple of sales pages that I looked at today where the site had a Youtube video that it looked fine until you clicked 'Play'. i.e. the opening image of the video is there but when you click play you get a black screen that says 'We're sorry but this video is no longer available'.
I decided to check one of my own sites and YIKES! the same problem. The video is not working.
I then went to my Youtube account, checked under 'My videos' and both videos are playing just fine on the Youtube site.
Better check your Youtube video's on your sites guys.