You don't have to install massextract, but you will need some dependencies:
pip install lockfile
pip install patool
./massextract.py --help for usage information.
If you want to extract and are not concerned with the integrity of files (say,
a media file is not finished downloading) then you can set the threshold to 0.
This will cause massextract to attempt all recognized files. You can later
force re-evaluation of these files by passing the