Hello,

After install Ubuntu 12.04 beta 2 - 64 bits to test it, I decided to try the Flash player. I decided to try the method created by Romeo-Adrian Cioba that I published Install Flash Player on Ubuntu 10.04 64 bits or Install Flash on Ubuntu 11.04 64 Bits.

native installer Flash Player 10.2 Preview 3
native installer Flash Player 10.0.45.2 (Seems more stable)

Give execution permission:

$ chmod +x native-64bit-flash-installer.sh

Execute it: (It will close your firefox!)

$ ./native-64bit-flash-installer.sh

Tested and working!

Sadly the repository version is not working for me, but this one keeps working.

Enjoy it,
Matheus

Reference:
http://www.myscienceisbetter.info/install-native-64bit-flash-player-10-on-linux.html