Here is a little script that i made that will get firefox(nightly) up and running with flash support.
Tested working with Gnome 64-bit firefox(nightly)
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# Prepare Directory's
pkill firefox
mkdir /tmp/fox
cd /tmp/fox
rm -rf /opt/firefox/*
rm -rf /usr/lib/mozilla/plugins/*
rm -f /usr/share/icons/mozicon128.png
mkdir /usr/lib/mozilla/plugins
mkdir /opt/firefox
# Download Resources
wget
http://ftp.mozilla.org/pub/mozilla.o...x86_64.tar.bz2
wget
http://fpdownload.macromedia.com/get....x86_64.tar.gz
wget
http://upload.wikimedia.org/wikipedi..._icon_2011.png
# Extract Resources
tar -xvf firefox-18.0a1.en-US.linux-x86_64.tar.bz2
tar -xvf install_flash_player_11_linux.x86_64.tar.gz
# Install
cp -R firefox/* /opt/firefox
cp libflashplayer.so /usr/lib/mozilla/plugins/
#Restart Backtrack to reload start menu icon's or goto menu editor and reselect icon
cp -f Mozilla_Nightly_icon_2011.png /usr/share/icons/mozicon128.png
# Done
echo 'Installation Complete'
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Alternatice link for orignal version of firefox if you do not wish to install firefox(nightly)
http://releases.mozilla.org/pub/mozi...x-15.0.tar.bz2