The voice is Alan Kay who lead the invention of the modern day Desktop computer / GUI. The system is probably a prototype of the Dynabook, a laptop / tablet for children.
The code is Smalltalk which Alan and team created while inventing Object Oriented programming.
You can play with Squeak, which is the modern version of this system.
It's incredible to see how many of the concepts in this video is still present in a modern user interface.