macbook pro cannot play online video,requires adobe flash player but i did install and it won't works

Go to this web site ONLY and download and Install it:

http://get.adobe.com/flashplayer

There is some movie stuff online that is NOT Flash. One of the most annoying is Windows media.

Microsoft convinced lots of folks to produce their conntent in Windows media. Then they abandoned the Mac verison of the Player.

But they did provide a substitute: Flip4Mac:

Windows Media on a Mac? -- No problem! -- The official Windows media Player on the Mac

(All you need is the free download, despite their attempts to Upsell the for-pay tools.)