Possible Duplicate:
How do I install Flash 10 for Firefox in 64bit
I am currently downloading 64-bit Ubuntu 10.10 but am seeing reports that there may be problems with Flash. I'm installing this for a friend and don't want to have to find fixes or workarounds, so I'd like to know beforehand if this is going to be straightforward or not. His main usage of Flash would be on YouTube.
i have the same 64 bits version and i install this firefox plug-ins and all work fine :
Flash-AID plug-ins :
Remove conflicting flash plugins from Ubuntu Linux systems and install the appropriate version according to system architecture.
Though , Adobe released a 64 bit Flash Player called Adobe Flash Player Square ( note : it is still in developement stage ) which you can try .
It enables native 64 bit support in Windows , Mac and Linux Adobe Flash Player Square
It can also be installed with a ppa :
sudo add-apt-repository ppa:sevenmachines/flash
sudo apt-get update
sudo apt-get install flashplugin64-installer
Source : Webupd8