I experimented with a short term support release of Lubuntu for fun. I decided to wait for Lubuntu to adopt the new lxqt desktop before updating the distro. Unfortunately firefox suffered due to this choice. Besides strange bugs it became impossible to use certain video players (YouTube for example). I was also constantly warned that my Firefox install was insecure. I needed to update Firefox without a package manager.

Solution
I downloaded the latest Firefox which came packaged as a tar.bz2. I started by extracting the contents into a temporary directory.

# Create a temporary directory
$mkdir ~/temp && cd ~/temp
 
# move the downloaded firefox to the temp dir
$ mv ~/Downloads/firefox-*.tar.bz2 ~/temp
 
# Extract the contents
$ tar xjf firefox-*.tar.bz2

Find your Firefox Installation
I needed to find my existing Firefox installation to overwrite with the latest.

# Find the current firefox installation
$ whereis firefox
firefox: /usr/bin/firefox /usr/lib/firefox /etc/firefox /usr/share/man/man1/firefox.1.gz

I had a look at /usr/lib/firefox at found the expected files I wanted to overwrite. After closing Firefox I proceeded to copy the extracted files from above (which were extracted to a directory called firefox).

# Install the new version
$ sudo cp -R ~/temp/firefox /usr/lib/firefox

I was able to start Firefox and verify I was running the latest version. Video players are now working against as expected. That should hold me over for another month or two when the new distro release comes out.