elgachon You can install a static build of ffmpeg like this:
mkdir ~/tmp ~/bin
cd ~/tmp
wget https://johnvansickle.com/ffmpeg/releases/ffmpeg-release-amd64-static.tar.xz
tar -xf ffmpeg-release-amd64-static.tar.xz
mv ffmpeg-*-amd64-static/{ffmpeg,ffprobe,qt-faststart} ~/bin/
When you're done, ffmpeg will be in /home/shelluser/bin
.