Many servers are not connected to the internet.
If you launch Books Online for the first time, it will try to connect to the net and it may get stuck if there is no internet connection.
You can add these reg-keys after initial sqlserver installation, so it will not perform the online search.
Bol will use these settings when a user lauches it for the first time.
So you can still install and use BOL on your db-servers without the need for an internet connection.