Simon Jary of PC Advisor notes that there are many ways of fixing the problem of YouTube freezing, including the user reinstalling Flash. If the user is using a Mac computer, he must click on "System Preferences," "Other," "Flash Player," "Advanced" and then "Delete All" before reinstalling.
Safari browser users have two other possible ways of fixing the problem. One solution is to enable plug-ins by clicking on "Safari" and then "Preferences," "Security," "Internet Plug-ins" and enabling the "Allow plug-ins" box. If this does not work, users can reset Safari by clicking "Safari" in the menu bar and selecting "Reset Safari" from the dropdown menu.
Firefox users must click on "Options" and then "Advanced" and General." Then, click on "Browsing" and remove the check from the button labeled "Use Hardware Acceleration when available."
Another possibility is that the user may be participating in the HTML 5 trial. If so, he can click on a button in the bottom left labeled "You are currently in the HTML 5 trial," which may fix the freezing problem.
Extensions and Add-ons in the browser may also cause YouTube to freeze. Disable all of these to see if it fixes the problem. If it does, experiment by adding the extensions and add-ons back individually until the one that is causing YouTube to freeze is identified.