Well as you know Adobe has not release a flashplayer for 64 bits, so for now you can use the swfdec a flash player compatible that come with almost all GNU/Linux distributions, how ever if you can used or it does not work for you, then try out the Adobe Alpha release.
To download the Alpha Adobe flash player for x86_64
If it does not download maybe the have a new release so check the first link.
To install it after download
tar xvz libflashplayer-10.0.32.18.linux-x86_64.so.tar.gz
After that copy the file to
cp libflashplayer.so /usr/lib64/mozilla/plugins