Need help with youtub why it say on ever video we'er sorry video is no longer available on youtub?

yes im shure i can see only about 5% of vidoe on you tub but 95% i cant not see if i go to a nother place like live videos web site i can see any one i want and yes i did dowen loaded the new flash a nother guy say he cant see videos there too but only 5 % but he whent to a nother pc and he could see all videos