At the end of November, Adobe Labs announced the long awaited release of 64-bit flashplayer plug-in for Linux. I checked around and there are numerous HowTo's providing guidance on installing the new, improved plug-in on a Linux System. Most are wrong.
Advice includes downloading the Flashplayer-plug-in tarball and adding it to /usr/lib/. Ignore the advice. If you run Google's Chrome browser, here's how to install the new 64-bit flashplayer plug-in. I run Debian Linux.
Check /etc/apt/sources.list. You should have contrib non-free added:
$ cat /etc/apt/souces.list
If not, as root add contrib non-free to your repository. Here's my sources.list:
deb http://ftp.uk.debian.org/debian/ squeeze main contrib non-free
deb-src http://ftp.uk.debian.org/debian/ squeeze main contrib non-free
Yours should look similar. I run squeeze. After you confirm your repository has non-free added, close and save the file.
# aptitude update
aptitude install flashplugin-nonfree
Debian will download and auto install the flashplayer plug-in. Close and restart Chrome.
Go to Youtube.com and check it works.
Mine worked first time.