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.
Give execution permission:
$ chmod +x native-64bit-flash-installer.sh
Execute it: (It will close your firefox!)
Tested and working!
Sadly the repository version is not working for me, but this one keeps working.