online videos i.e for example youtube videos are not playing in Internet Explorer 8, whereas they are playing in Mozilla firefox.also I have update my java and flash player.
Well, JAVA is not used with Youtube, anyway Were you ever able to play video's on that machine, if so when did it stop working? After a flash update?
I would reccoemend downloading the adobe flash uninstaller (HERE) and then re-installing adobe flash to see if that makes a difference
When you upgraded to IE8, your computer suddenly needs more memory than it did before. How much memory do you have? You probably need 1Gb now, but did not before the upgrade.