The new Facebook functionality to share and distribute files come with various restrictions. The restrictions include size (limited to 25MB), content (no executables and music) but files like pdf, music and other videos, comics, books and documents are all allowed.
The normal systems will be in place for users to report malicious, inappropriate, copyrighted files and other banned content, the same as users can already do right now.
There are over 380 million people that use Facebook Groups. Being able to share files was one of the most common requests from groups users, according to Facebook.