Why since firefox 4 upgrade, I now have jumpy video

Hello, i noticed that your flash player plugin is not up to date, please update a check if the problem persists

http://www.mozilla.com/en-US/plugincheck/

The plug in check process results in a stopped script message. Can you provide the name of the plug in needed for You Tube videos?

Thx in advance.

Yes, its Adobe Flash Player and you can get here: http://get.adobe.com/flashplayer/ Also i advise you to update java as well: http://www.java.com/en/

everything is updated and the problem still persists. It's not download speed, it is playback speed. Safari still works normally and gives smooth video playback. HELP!