Why can't I watch youtube?

So just about 30 minutes ago, I downloaded the newest version of adobe flash player. I went to youtube and clicked a video. It said "blocked plug-in" so i clicked that and it said "The version of 'Adobe Flash Player' on your system does the include the latest security updates and has been blocked. To continue using  'Adobe Flash Player', download an updated version from

adobe's website". I've downloaded the newest already. What is the problem? I have a macbook air btw. What should I do to be able to watch videos again?