Video on facebook cannot play !

There is nothing wrong with Flash Player or anything else. The "problem" is in Facebook. So as the title says, the video is removed from Facebook, or you can't see it because the privacy of that video not allow you.

Exactly. You can also get the same (or similar message) on YouTube, Vimeo, or indeed any other similar site. It doesn't mean that there is anything wrong with your computer, nor does it necessarily mean that there is anything wrong with the site. A video may be unavailable for a number of reasons. Firstly, it may have been removed, either by the person who submitted it, or by the site owner/administrator following a legal or other such request. Secondly, it may be temporarily locked so that it can be updated/modified. Thirdly, it can be restricted so that it can only be viewed by people in a certain geographical region and/or who have signed in to the site.

What browser you are using ? Have you tryed to run it in Safe Mode ?

Have you tryed clearing cache (Ctrl + F5) on that page ? Have you tryed to open the video in another browser ?

And for the end, use this method to uninstall Flash Player. Uninstall Flash Player | Windows

And, do you have that problems again ?

I don't think so that it's a virus... Maybe that's some kind of a bug from Facebook. Facebook is also excepting with problems a lot of times...