Hi,
If this problem is just with online video such as Youtube, try a clean installation of the Flash plug-in as follows.
First, download the Flash uninstall utility on the link below and save it to your Downloads folder.
When the download has completed, close all browser windows, open your Download folder and run the uninstaller. After this has completed, restart the notebook.
Next, ( unless you already have it ), download and install Firefox and then using Firefox, download and install the latest version of Adobe Flash. Note: You may want to deselect the option to include McAfee Security Scan Plus before downloading.
Close all browser windows before running the Flash installer.
Launch Firefox and see if videos etc play Ok in this browser - if they do, close Firefox, open Internet Explorer and click on the same Adobe Flash link above to get a prompt to install Flash. When done, restart Internet Explorer.
Regards,
DP-K