I accidentally discovery this one, it works!

- Press the Space key (long one) to pause the watching Video.

- Then use, the left or right key to backward or forward the clip!

That’s it!

Updated April 12, 2010

Solved by installing a native 64 bit version of the flash player

How to install:  http://ubuntuforums.org/showthread.php?t=1081964

Enjoy