Adobe Flashplayer Issues

Hi, everytime I try and stream a youtube video or anything of the sort I keep getting a message telling me that I need the latest adobe flashplayer or to turn my javascript on.

I know my java is on but when I try and d/load the latest player it never seems to work for some reason. I get a security message which I allow and click install, and then it refreshes the page and doesn't display properly but says it's installed, yet the problem persists.

Can anyone help?
Thanks