With https://whereby.com/ you can provide video meetings in the browser. Your attendees just need to visit your custom link to whereby.
You can also share your screen and for small teams (up to 4 attendees) it is gratis.
This is not a code library but a software recommendation. Anyway, i hope this helps.
In regards of security, Nordlocker is a good solution for file encryption with high privacy focus as well. It protects files with easy encryption process (drag and drop into the locker). Only you and people with password can access them.
It has a free option, which allows to encrypt up to 5gb of data for free. I started from this version three months ago ...