I Get Only Audio When I Expand YouTube Videos

Until a couple of months ago I was always able to expand YouTube videos to fill my monitor screen. Now when I try to expand them I get only the audio, none of the picture. Any ideas someone?

In need of a flashplayer update...?  Also saw someone suggested starting in non-fullscreen, right click on video and in settings uncheck "enable hardware acceleration" - but would think that only meaningful if you have a really dated video card or the like.

Ace; Hoosier

I cannot update to IE9, because I only have Windows 7.

I tried to install the latest version of Free Adobe Flash Player. In following their instructions to uninstall my existing Adobe Flash Player, I apparently became too eager and mistakenly uninstalled something called an "Adobe Flash Player Add On." ---- and I believe this is required in order to download the latest Flash Player (trying to download latest Flash Player has been unsuccessful).

I have been unable to find where to get a download of that "Add On." Help please.

IE9 is not compatible with W7

Just minutes ago I got a "Happy Birthday" message from "Tech Support Guys" forum. It said I hadn't been to their web site in ages. On a whim I went there, and when I clicked on "Forums" I got an immediate popup asking if I wanted to install the 11.1 version of Adobe Flash Player. This popup looked different than any I'd seen before , so I entered there and it installed the player and the player works okay and allows me to expand the videos with both audio and video.

I am completely, utterly baffled as to how this could happen!!

Sorry Ja, I guess I had a Gov Perry moment. I have WXP, not W7.

Thanks to all who answered me.