This video accompanies the post Greenhouse Gas Protocol: Four Scopes.
It provides an overview of the Greenhouse Gas Protocol, and the three scopes that it describes. (The fourth scope is not used much.)
The four scopes are:
Scope 1: Direct Emissions
Scope 2: Indirect Emissions
Scope 3: Corporate Value Chain Standard
Scope 4: Avoided Emissions
The post Scope 3 Emissions: Systems Complexity describes some of the difficulties to do with organizing and implementing the Scope 3 requirements.