This is a prerelease version of the Adobe® Flash® Player 10 software 64-bit Linux platforms. It is being made available for developers and consumers to test their content to ensure new features function as expected, existing content plays back correctly, and there are no compatibility issues.
You can download flash 64-bit version from here
Full Credit goes to here
1. Download the new flash from here.
2. Right click on the .tar.gz archive and choose ‘extract here.’
3. Open up a new terminal window and type ‘locate libflashplayer.so’
4. The results should show that there are two locations where flash resides, but this may differ for other people:
5. In the same terminal, type ’sudo nautilus /usr/lib/flashplugin-installer’
6. Copy and paste the new libflashplayer.so file from the location you extracted it into and overwrite the old one. Now inside Nautilus, navigate to any other locations that came up in the “locate” command – so for me it was the /usr/lib/mozilla/plugins directory. Copy and paste once again. Just be careful while you’re in Nautilus as root, as you have full access to all files and folders – so don’t overwrite/delete anything you shouldn’t!
7. That’s it, all done. You can verify it’s working by opening up Firefox and typing ‘about:plugins’ in the address bar. Visit YouTube and any other flash sites to check that it does indeed work, and you should hopefully notice a marked improvement in performance.