All forms of collaboration require some sort of centralized collaboration tool.
In Drupal this can be implemented with "Multi-Sites", "Organic Groups (OG)", and "Domain Access". These solutions all have their strengths and weaknesses.
The main issue however is when to choose "Multi-Sites", "Organic Groups (OG)", or "Domain Access".
First a short overview of the relevant points:
The easiest and simplest way to embed video in a drupal post is by just copying and pasting the embed video code into the content you are making.
As with all things drupal, there's also at least one module for this;
To install modules in order to customize your Drupal install: