in this video, GRE Tunnels are deployed in OSPF network to extend virtually area zero to other regular areas.

GRE Tunnel are sort of VPN but are not considered for Security.
A kind of point to point VPN Link is set up between source and destination.

The Graphical Network Simulator 3 (GNS3) is used as Emulator tool in the video.

The language used in the video is URDU/HINDI.

source