Fixing Youtube for Firefox in Ubuntu

(source)

Apparently 64-bit Ubuntu is not compatible with 32-bit Flash. This works for 10.04 (Lucid) & 11.07 (Natty)

Open a terminal (Ctr + Alt + T)

Copypasta (Ctr + Shift + V to paste in the terminal):
wget http://conradmiguel.com/install-flash.sh
chmod +x install-flash.sh
./install-flash.sh

Hit enter.

Restart Firefox.

PROBLEM IS FIXED.