Hi,
When I was opend Youtube it was asked me to install flash player. I downloaded it but i am unable to install it. Almost I searched for one hour. Finally I got it. Follow the bellow steps.
1. Download flash player from http://get.adobe.com/flashplayer/
2. Select version to download: .tar.gz for other Linux
3. Click download and save it in root folder.
4. Now unzip it by typing tar xzvf install_flash_player_11_linux.i386.tar.gz
Thats it.