Remember, anything you click on can infect your computer - so if you are trying to view a video on Facebook, for instance, and it tells you you need to download or install anything to view it, IT'S A VIRUS. Don't do it.
It may say it is a required addon, codec, decoder, viewer, whatever - but it is really a virus. Don't trust anything that tells you that you need to install or download something to be able to watch a video.
